Issue Needing Help Guys...

[53GMC]

I have a 1996 Chevy S10 4.3L V6 .....lately my truck has been experiencing a strange problem that just showed up a few weeks ago...then went away,..then came back...and im really confused..

when you apply pressure to the gas pedal it will try to shut off.....so i cranked it back up and let it idle...after about a minute of idling i tried to apply a little pressure to the pedal and it tries to shut off again...if i stop pressing the gas pedal before it shuts off it will stay on but runs a little rough....if i crank it and try to back up or pull forward it will try to shut off also....just not really sure where to begin....

thought it might be the fuel pressure but have not had this problem before....im stumped and need help...

thanks again guys...

Blake

[lvschevytrucks]

Sounds like a fuel filter to me. Ive Had that problem before and its always been the filter

[lakeroadster]

I agree, sounds like a fuel filter. Getting any "check engine' warnings?

[dubds10]

Check spark plugs, wires, cap and rotor as well. Those will cause similar problems as a clogged fuel filter. I was having the same problems with my s10 and I looked at my cap and rotor and they were toast.

[53GMC]

Thanks guys....i will check the fuel filter out...i checked my spark plugs and wires but i will check out the cap and rotor also....i didnt know that could cause similar problems....I haven't been getting any check engine lights but the whole fuel filter thing sounds like the thing that could be causing it....why would it not cause any problems with the engine idling but when you push the pedal it does this...is it because the pressure increases and the fuel filter is then clogged with the pressure of whatever is in it? just curious about the underlying causes

thanks again guys,
Blake

[lakeroadster]

Originally Posted by 53GMC

Thanks guys.... why would it not cause any problems with the engine idling but when you push the pedal it does this...,
Blake

It has to do with the quantity of fuel required. Not much is needed at idle, but when you push the accelerator down the engine needs more fuel, it goes lean starts to die, then as the motor slows down it needs less fuel, recovers and then idles again.

I had a SBC that would fall on its face when I would go to pass a car, but would run fine at cruising speed..... I replaced the fuel filter and it fixed the problem.

[53GMC]

Thanks...that helps me understand much better....I will replace the filter and see how it does!

[53GMC]

i changed the fuel filter and what-a-ya- know that was it! I never doubted ya'll and thanks again!

[53GMC]

well guys....i spoke too soon.....the same problem started again....any thing else could be causing this? could the new filter have gotten clogged up with some more trash?
thanks guys...

[dubds10]

Did you check the cap and rotor? I know you said you checked the plugs and wires.

[lakeroadster]

Originally Posted by 53GMC

well guys....i spoke too soon.....the same problem started again....any thing else could be causing this? could the new filter have gotten clogged up with some more trash?
thanks guys...

Yes, very possible. What type of fuel filter do you have? You can take the element apart and look at it to see what is cloggin it. Is it little chunks of rubber or rusty looking stuff? If you have rubber fuel line it may be deteriorating, or it could be sediment from the gas tank.

Also, some carb's also have a small sintered brass element filter where the fuel line attaches to the carb. as well as an in-line filter.

[53GMC]

my fuel filter is an in-line steel line filter....its easy to take in and out but not where i could take it apart and look through the filter element within in....gonna try putting in another one this weekend and see what happens....could it be the fuel pump or injectors by chance?

what should i be looking for exactly when i check the distributor cap and rotor? what would it be affecting with the fuel system? im just ignorant so please excuse it haha

[lakeroadster]

Originally Posted by 53GMC

my fuel filter is an in-line steel line filter....its easy to take in and out but not where i could take it apart and look through the filter element within in....gonna try putting in another one this weekend and see what happens....could it be the fuel pump or injectors by chance?

what should i be looking for exactly when i check the distributor cap and rotor? what would it be affecting with the fuel system? im just ignorant so please excuse it haha

I would think if it were a distributor problem it would be misfiring, backfiring, etc.

If the fuel filter fixed the problem, even though it was temporary, I wouldn't stray to far from that being the problem, my 2 cents. When you take the fuel filter off take a white cloth, like a diaper or old white tube sock, and blow some air into the fuel filter outlet so the gas comes out of the fuel filter inlet, basically back flushing it onto the white cloth. Look at the white cloth for small chunks of "stuff".

In any event.... Distributor: take the cap off and look inside for cracks. Also look at the copper electrical contacts inside the cap for wear or signs of electrical arcing. As for the rotor, same kind of deal. Make sure there are no cracks in the plastic and that the contacts look ok. And that it seats solid onto the distributor shaft.

I had a Nova back in the mid '70's that had a cracked distributor cap.... it was driveable, barely, but backfired and misfired something awfull. Also had the wrong rotor cap once on a Ford 5.0 HO, it chewed up the inside of the distributor cap.

Good luck and keep us posted.

[53GMC]

Thank you so much lakeroadster...the guys on this site are awesome.. i will do that with the filter - didnt think about back flushing it. would the fuel pressure regulator affect this situation any? gonna try to clean the little screen inside of it too when i get back home later this weekend...thinkin maybe it is clogged up....if there is some in there then maybe i will be able to see it for sure.. the tank is about 1/4 full if that much and i was thinkin about draining the gas tank...thinkin maybe good bit of debris in the tank keeping it clogging up....would like to drain it and clean it out some maybe....

im used to working on old tractors and usually i could see the debris in the little glass bowl the gas runs through...but this situation is like a tractor on steroids haha

[dubds10]

I had two fuel pumps in my s10 go out on me and they caused similar problems as well. The dist/rotor will actually cause the same problems and stall the vehicle. It'll only misfire when you step on the gas while driving, but it's more like a loss of power similar to that of a clogged fuel filter or fuel pump dying and not feeding the engine enough gas.

If you haven't done a tune-up on it in a long time, then it might just be a good thing to do while you're at it.

[68C15]

aside from checking fuel pressure and volume you could unplug the mass air flow sensor while it is running and acting up. if it runs better you have a bad MAF.
when unplugged the ECM calculates (assumes) amount of air flow by looking at engine speed, air temp, engine vacuum, and throttle angle.

[53GMC]

hey guys....i replaced the Idle Air Control Valve and the throttle regulator and the fuel filter and drained all of the old gas out of the gas tank....now it is running good...that is... when i can get it cranked.

if i spray a little bit of starting fluid down the throttle it will fire and crank no problem...then it runs great....

but if it just sits there for a few hours and then i try, i cannot hardly get it to crank.....the fuel pump will cut on and it gets up to almost 60psi but then it goes right back down to zero....so...thinking fuel pump guys?

[bighaas79]

if you are bleeding off fuel pressure it is basically 1 of 3 problems, fuel pressure regulator is bad, check valve in pump is bad, or injector is stuck open. Check valve requires replacement of the fuel pump, and either the regulator or the stuck injector requires the removal of the upper plenum to correct either problem. If you are having problems with it starting and a shot of starting fluid will pop it off i would guess check valve. you can try to turn key on a couple times and then crank it over. If it takes off your gonna be pretty sure its the check valve. The regulator can be checked with a small mirror stuck down the the thottle body with some good light. I use a boroscope but most people don't have access to one.

[53GMC]

thanks bighaas....i will replace the pump and check the regulator also...i will get back to yall what the problem is

[Chevy350V8]

Im thinking the pump, let us know!

[53GMC]

i just bought a pump.....will put it in tomorrow...then i will let you know the results....wish me luck

[53GMC]

installed the new fuel pump...issue resolved....thank you guys for all of your help!

[gchemist]

Nice work. I need to order a fuel pump myself. Mine has 191500+ miles on it. The previous owner had records for almost 5 years. I've had it for 3 and the pump has no record of being changed. Pressure sometimes drops to 50 PSI. I know it's only a matter of time before it fails.