Fuel electrical FIXED!!!!REALLY long please read all...

does ANYONE know where the fuel prime connector comes from?????

fuel pump relay
#1- ground-0.0 ohms to ground  
#2- pcm fuel pump relay control- has continuity from pin "d1" (autozone 1996 wiring diagram printout) (black connector pin #1 on vcm green/white) but no voltage with key on or off
#3- + common point on relay which switches from #4(fuel pump prime connector) and #5(fuse#9 ECM Batt Cir)- works when shorted to 12v + source
#4- Fuel pump prime  connector... (WHERE DO I FIND THIS!?!?!?!) where does this come from or where is it triggered
#5- +12v power source- verified 12+v

also does anyone have the wiring diagram for this fuel circuit??? including fusible links and connector locations.. or even better a FSM for 1995 in pdf???? 
* edit #2 heres videos of the tests

video#1-http://www.youtube.com/watch?v=pVmtiqN-wKU
     #2-http://www.youtube.com/watch?v=20jKwJnSB5k
    

Please have patience.  There is no need to double post the same question in multiple sections.  I will get to this when I get home and have my references on hand.  While I am at work, I cannot answer things which I do not have direct first hand experience with.  Hopefully before then someone can answer it, but if not, patience must be excersized.

yeah I couldnt delete the post I didnt' realize I put it in the engine tans section so I tried to post in the correct section.. as for patience... i do have some butthis fuel one jsut happens to be a bit of an issue at the moment.. (friday raining) tomorrow rain/ clearing sunday great day to fix it monday job and oh yeah the car inspection I was supposed to get on friday.......... it's not impatience it's urgency.. and desperation.. and as far as the other posts.. I'm on here and they were on page three... withno replies.. which I read from you was ok to bump if it hits page two with no replies.. so i was merely bumping....
 
*1 edit tho now that I think of it I have a few more questions to add...
 
what is the block on the driver side with all the ( what looks like fusible links)??
where I only have voltage on the #5 pin and theres a minimal spike on the "prime connector" which comes from the pcm.. could the pcm be causing the abs,brake,ses/hesitation issues?? 

I saw no problem with your bumps, which is why I didn't comment on them.

*EDIT* - that sounds...  bad...  LMAO!

love my bumps all you want your'e still not gettin my sam adams:-P

I am not completely sure where the fuel pump prime connector is, but it may be in the instrument panel fuse block.

The relay is the one to the driver's side behind the glove box.

Here is the schematic for the fuel pump wiring:

AWESOME but now I'm gunna soudn needy... :-( is there a schmatic available for the vcm,fuse block details, insturment panel details, and ground points(from other post about abs).. i checked continuity from the vcm to the relay socket (slight discrepancy between connectors onthe diagram you provided it has it labeled as C2 "blue" on the vcm red and blue are on the bottom.. gray and black are on the top and the wire comes from the top rigth side facing the truck I belive its the black connector..( not in front of me at the moment) )) but continuity from the green/white trace wire to the "coil" pin in the relay socket and measured 0.0-0.1 ohms.... which should be fine..but when I actually check for voltage..(I'm assuming 12v to pull in the relay coil ) key on engine off... and I have (whats in the video).. spikes to 0.151v then nothing...

*side note doesnt the abs control module get its feed from here"vcm" or is it jsut the parameters...

I have a second vcm the guy gave me ( and was charged $125 to program it to the truck) but he said it did the same thing.. wouldnt stay running long.. etc..(that was fpr) but he also said he had a hard time priming it.. he said he got it started when he replaced teh eprom in the vcm) I'm wondering if it's either the vcm dying or somethin with a harness at that point... but without a pinout of the vcm I'm kinda up craps creek... thanx for all your help:-)


btw
earlier post...* edit #2 heres videos of the tests

video#1-http://www.youtube.com/watch?v=pVmtiqN-wKU
   #2-http://www.youtube.com/watch?v=20jKwJnSB5k



edit#3 k few things....

-first I tried swapping the eprom(eprom#2 in vcm#1).. for giggles... didn't work..

-then I tried finding that damn connector.. well come to find out henr3 posted a howto on this awhile back and its a red wire with a female connector end on it... THATS THE FUEL PRIME CONNECTOR!!!!!!!!! it's a test line that goes to the normally closed side of the relay where the common goes to the fuel pump... so if you suspect your fuel pump is dead you hook this fuel prime connector to a 12+v source and if you hear the whirring your fuel pump is working... if not.. then chances are its dead... mine whirred so fuel pumpseems to be working..

-then for more giggles I swapped out the vcm(vcm#2 with eprom#1) well I get everythign connected and put the key in and turn it on to prime it.. the relay is clicking like crazy along with the brake lights and abs lights like a loose wire... (dunno if its loose or the old vcm#2) but after a little bit its primes and stops i turn it over it starts.. but after a few minutes it dies..no warning.. jsut dies. it'll prime and start right back up again.. I'll post another video.. so my question..

is this looking like a vcm... or ground or loose harness????


keep in mind this vcm (vcm#2) I've never tested.. the guy I bought it from said he thoguth that was the issue too.. and he replaced it and paid a shop$125 to program the eprom for the truck..... I dont knwo what else could make the truck stall out periodically..
any ideas???

please and thank you in advance

edit#4

k well this will be the last update for now I will post the solution once i find it... the truck starts and runs... tho when i went out this morning and stuck the key in to prime it... the relay clicked on and off about 3-4 times in abotu 2-3 seconds.. then it click on and held till it primed and shut off and started right up
so I guess I'll dirve it for now.. (ALOT of backed up side work from not having a vehicle).. and when I get a chance and a warm day to strip it down and actually FIX it...lol but if anyone has the same issues.. like swart said  check ya grounds... the fuel pump prime connecter is by the fuseible link box on the driver side inner fender wall.. look around under the harness it'll be a red wire with a female connector... you can tap it right to the termi

hmmm 4th page... 9 days... no replies or solutions.. BUMP... yell at me if you must.. desparate times call for desparate measures.. perhaps i have the only blazer that has ever had this issue???? any ideas...????

Is the voltage signal fluctuating at the VCM output to the relay (C2-blue F6)?  How about the oil pressure signal to the PCM (from the schematic I posted above)?

Have a look at the following images:



Sorry you had to go through all of that updating, but man..  If it falls off the first page, bump it.  The stigma against consecutive posting is when someone does it within 24 hours of the prior post for no reason other than they forgot something.

ahhh gotcha on the posting.. um the thing is those charts dont apply to my vehicle.. but where did you find them cuz I've been looking for something like that I have the alldata diy subscription but I can find anythign like that on it.. and I have 4 connectors.. gimme an hour or so to get pictures... ignore the crimps that was me tying to bypass any possible shorts... if it worked I'd do a proper patch ( solder, heat shrink and silicone sealant )  but it didnt.. so I still have to do a proper patch once I get it running. as for the oil pressure switch.. i hear the relay erratically clickin over once pressure builds up.. but before even with engine cranking i had no click from the relay at any point..(oddly it would say oil pressure wasnt building)... but when I put my foot on the gas... and then cranked it would build pressure.. jsut low.. but enough that it should have started.. and now i have 2 issues... my fuel pump relay is pretty sporratic more often then not it clicks but doesnt seem like a good connection.. and I've done this with both relays and tested themm right with battery voltage they both work fine... and now I have no spark... coil tests fine... dunno if I can test icm without a computer.. and jsut got a NEW set of wires cuz most of them were out of spec...(3weeks old) bosch premium wires 4th set in 2 years .. correct me if I'm wrong the vcm controls both spark and fuel signals correct?.. vcm tells icm when to fire ic... and vcm controls fuel prime... then oil pressure switch controls fuel pump once pressure builds.. and I can almost certainly say the oil pressure switch is working because I (being the genius that I am ) had someone crank it while i "sniffed" the exhaust... good thing noone was smoking near it.. holy crap....yeah its got gas... so any idead where I can find those charts with my connectors?

Ok, I pulled those from the most common VCM-A setup, but you have the PCM setup.  95 was truely a VERY screwed up year!

I'll grab the other ones tonight.  Hopefully I can do it the same way I grabbed those with minimal rework, LOL.  I got those from an AllData service DVD I have access to.

ummm I'm hoping you have vcm-a and pcm confused.. because all of the wiring diagrams that most fit my vehicle have been from vcm-a....  color codes and pin locations on vcm-a harnesses
 
heres a post I found on obdii.com
 




#14106 - 01/22/02 09:02 PM Re: 1995 Blazer

Finz Finz
Junior Member


Registered: 01/21/02
Posts: 3






Offline
Thanks for all the inputs. I received an E-mail of how to tell the difference between VCM and VCM-A. For those who are interested; VCM has (3) larger cable assemblies side by side, and a forth (assumed pwr cable) also in horizontal line. The VCM-A has (4) larger cable assemblies double stacked 2 & 2, one over each other, with what I'd call the pwr cable centered on top row, (5) total. The VCM-A also shows ribbed heat sink fins vs flat for the VCM. VCM-A has connections on Pins 2,4,16 on the schematic, while VCM shows pins 4,5,6,9 as being populated. Since VCM has no pin 2 connection this would not have a chance of working on an OBDII scanner. Only the VCM-A has a chance. Since I know someone else who has a 95 Blazer also can't read out codes with the Actron scanner, I'm not suspecting a computer problem just yet. At least at this point I can tell the scanner sales folks I've got a VCM-A. I'm getting closer!

yeah, sorry, my mistake.  Going from memory and typing fast while at work.

ok kool.. and I found two issues.. one is the oil pressure sensor terminal C has 0Volts key on or off.... though terminal GR21 has 12 volts and fuel pump relay terminal 5 has 12 volts all orange wire from fuse #9 ..just as soon cut it and patch in a new feed from a clean spot by the vcm pin GR12... and the second issue I have is a little odd (like this whole darn thing isnt) well the ignition coil control/driver module terminal C had 7.5-9.0 ohms, 0.006 volts with the key in the run position...even with a new ground paralleled to it... same results... with the key off.. it has 0.0 ohms...0.000 volts.... so where do I go from here??? it says on the schematic this is a ground...  can I jsut cut this and abandon the black wire(wherever its shorted to ) and install a clean ground of my own????  these would both explian the stalling while running.. ops... and the no spark.. icm... no ground... or weak ground signal.... sound like a plan???.. otherwise I think I'm looking at ripping out a good chunk of the wiring harness and laying it on the ground.. and wire by wire going thru the damn thing... looking for nicks or abrasions or sharply bent wires that could have possibly broken in the insulation... so OTHER THAN THAT.. how do the other ideas sound????

I'm afraid that without being there, seeing what you are going through, it is very difficult for me to offer up an opinion of what is the proper way of going through this stuff.  Wiring problems are one of the MOST challenging problems that anyone can come up against in a modern vehicle.  I am not fully sure that I could even research the problem enough with the references I have access to inorder to be able to help you more with the limitations that are present (over the internet vs. in person).

Attached below you will find the connector views for the VCM-A setup:

awesome thanx for the info..  and yeah I'm assuming as much wihtout being present its hard to diagnose.. and like I said before << licensed electrician... the small question I have I didnt SEE any splices for the ignition coil ground.. so that should be a clean singular ground coorect.. and if so... I can snip and patch on my own... but I have a gut feeling theres something pretty mangled in the harness.. cuz none of this answers the prime relay issue....
 does this at least SOUND logical?? provided my back feels better tomorrow I'm going to implement these things and give it a ****in whirl.. the thing I'm not sure of is why when the key is on I get a resistance to ground on the coil connector.... very odd.... but alas I will post my findings.. maybe this was a more common issue with the 95s... since I've found at LEAST 4 with the same issue...  but none of them posted results... this doesnt take into account how manyjsut burned the trucks for being such a pita...lol

This might help:

yeah I have that thats the diagram I'm refering to with terminal C of the icm...  but would it be safe to say????.. key on or off that shouldn't affect resistance????... that should jsut be a solid clean ground????
....( the resistance indicates to me that wire is shorted in the harness somewhere to another wire... or few)
 

Yes, that would be a proper assessment.  I would be worried that it might be shorting with some other wires in the harness...  Maybe find where that ground is in particular and what wire at that ground location is the one that runs to the ICM and cut it there as well as at the ICM.  If it is shorting out inside the harness, you really should find out where...

yeah I'm gunna work on that tomorrow provided I can move I dunno what I did today but I did somethign to my back.. drugs, alcohol and a heating pad later... I'm still in a lil bit of pain.. so this may be waiting a bit longer... but Ithelps to be able to bounce ideas off others.. and it helps knowing I have a lead and a direction to head on.... thanx for the help.. I'll be posting every step...:-P

Well my computer froze so I hope I'm not double posting.
 
I have a 97 Blazer 4.3 with a fuel starting problem pump/regulator. Got the fuel pressue gauge reading was low. Thought it may be the fuel pump so I purchased one, than I went to the manufacturers website and found these informative videos and wanted to share. Hope it's OK to post a link. the videos are on the left side down abit DIY
 
I will be preforming additional testing before installling the pump, wish I went to these videos before buying.
 
How would you rate a Carter fuel pump, I know it's recommended to purchase a good quality over saving money on this part.
 
http://www.carterfueldelivery.com/fuelpumps/consumers.php#

yeha but if you read the first post and subsiqent posts.. pressure isnt the problem....... I wish it were THAT simple... I couldnt find the issues.. I ripped the harness out till i got to the driver side head.. wondering why I couldn't pull it out I guess that's where both left and right side harnesses go down towards the transmission and associated crap down there... so short of ripping the whole darn harness out.. I snipped the wires.. leaving enough to splice back together later if need be.. and spliced the oil pressure sensor according to the diagram tho oddly.. pin 21 grey vcm-a connector which i spliced to oil pressure sensor terminal C doesnt ring out to  fuel pump relay terminal 5... they all NOW have 12 volts with key on.. but I'm wondering why this is... as far as the coil ground.. I left it as long as possible incase I have to resplice it to the original wire.. but  put a ring terminal on it and i plan on mounting it to the ignition coil mounting stud along with another ground that will go right back to that clean ground spot on the front radiator support.. which again has a 0.0 ohm resistance to the negative battery terminal.. this all still sounds right.. so we'll see how it works in practice... I'll keep ya posted...

Oops sorry about that, I was really trying to just post the link, could have used it myself before. Thought is was pretty close to what you're posting about, but what do I know? It included fuel??

there's PLENTY of posts on here for people with fuel PUMP issues.. this one is more pertaining to electrical .... as you can see if you read the previous posts


*UPDATE*

k so got everythign back together.. and i stick the key in .. turn to on.. and wait.. no prime.. have it crank... oil pressure builds.. fuel pump relay now clicks with oil pressure switch...actually funny it wont prime when I jsut turn it on.. but if I LITERALLY let it turn for one to two revs... it while prime until I pull out the key...
*edit* after reading this I had to clarify^^^^^^


theres no prime with the key in the on position intially  when I crank it the relay does click and you can hear the pump run as pressure builds like its supposed to... when I return the key to theon position from cranking back to the run position it will prime then cut off like its supposed to.....

if turn off then back on it will not prime but if I crank it 1-2 revs and the return to run it will prime.. ) kinda odd... hence the VCM question,,

*edit*^^^^^
but I STILL have no spark... I was hoping to avoid having to replace everything associated with the ignition... like I said before the coil TESTS fine... everything ohms out within range.. again no way to test the icm... OR vcm... so lets start a pool who's goin icm who's goin vcm...


stuff done

-new fpr
-new cap
-new rotor
-egr clean screen
-new acdelco plugs
-new bosch ultra premium wires( I KNOW AZ doesnt carry delco) and they were free (warranty)
-cut and conneted the oil pressure sensor switch terminal C to pin 21 on the grey connector giving it now 12votls when pressure builds...
-cut and put ring terminal on the ground for the icm placed that underneath the IC stud along with a #12 ground that goes from that stud to the clean ground on the upper radiator support which has 0.0 ohms to the negative battery terminal... so again .. POOL.. ICM or VCM...
??????????????????????????????????????????
 
OH and one other thing.. vcm.. when they say it has to be flashed.. what gets flashed.. the VCM itself or the eeprom inside????

k well new stuff.. I found a vcm-a from a 95 jimmy slt with all the same options as mine...  and it seems that the fuel pump relay issue has gone away but I think all this cranking and testing is wearing on the battery....
 
I used two flow charts... tho I don't know if they are applicable to my vehicle.. but here they are please read thru them as I have highlighted my issues.....
 
engine crank no start flow chart...
 
Step
Action
Values
Yes
No
1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? N/A
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check
2
Check the spark plug wires for open circuits, cracks or improper seating of terminals at the spark plugs, distributor and ignition coil before proceeding with the test.
Check spark at the plug with the J 26792 spark tester or equivalent while cranking. (If there is no spark on one wire, check a second wire). A few sparks then nothing is considered no spark.
Is adequate spark present?
--
Go to Symptoms
Go to Step 3< my situation.. 
3
Remove the coil wire from the distributor cap.
Insert J 26792 spark tester into coil wire and clamp the tester onto a ground. (used screwriver to stick in and test against good ground.... nothing!!)
Crank the engine.
Is adequate spark present?
--
Go to Step 12
Go to Step 4 **< my situation
4
Measure the coil wire resistance using a DMM. The resistance should be approximately the specified value.
Is the resistance within the specified value? SORT OF
1000 ohms/inch  8"-10" ~ 3.4k ohms
Go to Step 5 ***<<my situation***
Go to Step 30
5
Disconnect the ignition coil harness connector.
Probe the ignition coil connector terminal C with a test lamp connected to B+.
Crank the engine.
Is the test lamp flashing while cranking the engine? SLIGHT issue with this one.. I don't have a terminal C I only have A (white wire) and terminal B (pink wire) so I did the test with terminal a since it also splces to the tach wire.... and it DID flash when I had someone crank it
--
Go to Step 7 <<<my situation***
Go to Step 6
6
Turn OFF the ignition.
Probe the ignition coil harness connector terminal C with a test lamp connected to B+.
Is the test lamp ON?
--
Go to Step 27
Go to Step 8
7
Turn ON the ignition, with the engine OFF.
Measure the terminal A voltage with a DMM connected to a ground.
Does the voltage measure above the specified value?SAME thing SLIGHT issue.. I had to go to Terminal B and I did have the 12v(11.59V)  
10.0 V
Go to Step 20 <<< my situation...*****
Go to Step 17
8
Turn OFF the ignition.
Disconnect the ignition control module harness connector.
Check for an open circuit between the ignition coil harness connector terminal C and the ignition control module harness connector terminal D.
Is the circuit open?
--
Go to Step 26
Go to Step 9
9
Disconnect the ignition control module harness connector.
Turn ON the ignition, with the engine OFF.
Measure the voltage on terminal A at the ignition control module harness connector with a DMM connected to a ground.
Does the voltage measure above the specified value?
10.0 V
Go to Step 10
Go to Step 18
10
Probe the ignition control module harness connector terminal C with a test lamp connected to B+.
Is the test lamp ON?
--
Go to Step 11
Go to Step 22
11
Disconnect the ignition control module harness connector.
Probe the ignition control module harness connector terminal B with a DMM set to the AC scale connected to a ground.
Crank the engine.
Observe the voltage while the engine is being cranked.
Is the voltage between the specified values?
1.0-4.0 V
Go to Step 19
Go to Step 14
12
Remove the distributor cap.
Check the cap for the following conditions: