1996 starting problems

Just got this blazer and everything works great except trying to start it after it has sat over night. It will crank fine but will not fire. I have checked to see if it has fuel pressure (need a gauge which Im getting tomorrow) and spark and it has both and it cranks fine. Changed the fuel filter and it hasn't helped any. It seems the longer the truck sits without being warmed up the harder it is to start. When I checked the battery with a voltmeter after only cranking it 1 time it was reading 12.18 volts and this seems a little low but when I had the battery checked it was supposed to be fine.

any help would be appreciated.

Could be a bad ground somewhere pulling juice from the battery. I have no idea how you would find such a thing.

12.18v on a battery with the engine off isn't a bad voltage. I believe that 12.5v is ideal and I've started up our tractor trailer on less than 11volts before (granted it has 6 batteries). With the truck running, you should read ~14.5v at the battery.

Also, batteries can check out fine and still be at a low charge. If it were just a low charge, a little jump and idle time should bring it back up to full charge (if it won't start the truck itself).

Also, you really need to check the fuel pressure. If necessary, put the key in the 'RUN' position and wait for alittle while, then try to start it. You might just have a weak pump or a leak in the system somewhere allowing all of the fuel to bleed out of the system overnight and you aren't allowing enough time for the pump to build the pressure back up.

Get the fuel pressure gauge and report back as to the pressures. Check it with the key just in the 'RUN' position with the engine off, then shut off the key while you monitor the fuel pressure. If it bleeds down, you have a leak somewhere and unless you want to fix it, you'll just need to let the pump prime up before you start the truck every morning.

Keep us posted!

I have a 96 S blazer having a simalar problem. Everything worked fine but sometimes wouldn't start. Trying and trying would eventually flood it, then when it started it would idle at 1500rpm.(Wooooo). I couldn't find the problem and it wouldn't set any codes, so I had to pay a shop to fix it.
Turns out the truck was about to burn.
The egnition wires inside the column were shorting out. $160.0 for used column harness and labour and its good as new.

Good luck

I still haven't made it to the store to get a fuel pressure tester but I really don't think its lack of pressure, it has more to do with the temreture of the engine. Last night when I wen to work I got there at 10:30 and shut the truck off and went out and started it every 2 hrs to see what it did. at 12:30 it started fine, I let it run for a minute. When I went out at 2:30 it had a bit of a rough start but no excesive cranking. at 4:30 I had to crank for quit some time and it had a very rough start. at 6:30 when it was time to go home it was long cranking rough start and I had to press the gas pedal. Tonight when I went to leave after it sat for some time I tried start and of course it wouldn't. Due to what I thought was low battery voltage i tried jumping it and it fired on the first try with no problems at all.

Hopefully I will have time to get to the store to get a FP gauge but Im selling my old car and need to remove the electronics and getting ready to move so its a bit tough to get free time at the moment.

While your at teh store buying the fuel gauge. Get your battery tested. Sounds like you have a dead cell.

I bought a new one yesterday as it was borderline good and it had the same problem today. I put some injector cleaner in and have the gauge, now i just need to wait until tomorrow morning to see if thats it. If im reading corectly these only have one actual injector and I'm wondering if its sticking when the engine is cold. Hopefully tomorrow I will have a little more concrete info.

Fuel pressure is fine right at 60 lbs. Although when the the key is shut off the presure climbed to around 70 PSI and held steady for atleast 5 minutes before i bleed it off with the gauge. This morning after having put the injector cleaner in yesterday and taking a long drive it has got a bit better. It still has trouble but now I don't need to have a jump when I start it for the first, it just takes a few tries.

Something tells me that your fuel pump isn't shutting off when you turn the key off. Your fuel pressure should not rise when the engine is turned off... I'm wondering if that high of a fuel pressure isn't causing the problem. If it isn't now, it will cause some problems later on. 70psi is VERY high for the system to see. Almost sounds like an FPR issue to me...

On a side note... The computer is not the only thing that determines how much fuel is injected into the engine; fuel pressure also factors into this equation. The higher the fuel pressure, the more fuel is injected. The Fuel Pressure Regulator regulates the fuel pressure. The computer does not control the FPR; it is controlled by engine vacuum. There is a vacuum line that goes directly from the intake manifold to the FPR. Inside the FPR is a diaphragm with a valve. At idle when engine vacuum is high, it opens the valve lowering fuel pressure. At higher RPM's when engine vacuum is low, the valve closes increasing fuel pressure.

Im not getting any fuel to come into the cylinders when im having this cold start problem. I can crank for 10 minutes and as soon as i put on the jump from a running car it starts up like nothing was ever wrong.

Some times when I turn the ignition to on I do not get any light on the dash and if I tried to turn it on it will not. I would have to turn the key off and on to make sure the light on the dash turn on and then the truck turns on. Does this happen when it does not want to start?

ivannj, that is a tell-tale sign of an ignition switch problem (key switch). Sooner or later, it just won't do anything.

smplgrn, I'm wondering if you don't have an intermittent bad connection on the fuel pump relay. All that it would take would be alittle bit of corrosion on the trigger line (either 12v+ or ground) and it wouldn't trigger the fuel pump to turn on. I just recently traced a similar problem down to a faulty connection at the fuel pump relay on a '93 Ford E350 moving van. Cleaned out the connectors with a very small set of files that I bought specifically for this purpose and the thing fired to life after sitting for over a year. See the trigger lines for relays are 12v+, but very VERY low amperage because the trigger only has to energize an electro-magnet to pull the contacts on the high amperage side together (that click you hear when a relay switches).

During this cold start problem do you hear your fuel pump whirl to life when you turn on the key?

The saga continues

Today I tested the fuel pressure and it was at 50-52 PSI which is to low. I have yet to use the test port to bypass the relay but as soon as the jumper vehicle get on it raises the presure to 60. Sometimes if i cycle the key a few times it raises the pressure to 60 like it should be but this isn't usually the case. I thinking/hopeing probably a bad conection at the relay or pump. i have never had a pump that just weakened a bit, usually it's all or nothing.

What is the big electrical connection block that is located right by the test port for? the previous owner had a cd change powered at this point which I now have disconected.

Turned out to be the fuel pump. just not enough pressure