I'm having a problem with my pickup;
It's a 1991 Chevy S10, 2WD P/U, 2.5L I4 engine with around 185,000 miles on it. It's the Iron Duke engine, a throttle body injection motor. I'm not a mechanic, please forgive me if I use the wrong terminology.

Within the past two weeks, it has started to act a bit silly and I don't know what's all wrong with it.
It started as little hiccups while driving, not like a surge, but I'd be cruising along and it'd hiccup- a sort of feeling like it didn't fire on a cylinder. One note, I do recall when it started happening that I would smell gasoline for a few minutes after starting it while cold.

Then it got worse and worse with those hiccups. After that it started having a number of other issues, such as power loss, really bad acceleration, stalling, and a really rough idle.
Normally it idles around 950-1050 RPM, what has been happening is that it would start, idle high, around 1500, then drop to normal, and then start sputtering and RPMs would fluctuate anywhere between 750 on the high side, all the way to 0, stalling the motor. If I pressed the accelerator, it would either not affect the RPMs, or it would start to die out. Other times the motor would crank but not start at all.
I took it to an autoparts shop the other day to get some stuff to work on it, when I came out of the shop, it wouldn't start, and I popped open the hood to take a look. I took off the air filter cover, and pulled the throttle a little bit, got some fire/backfire out of the carb.

I've also had problems where when I would be stopped, put the truck in first gear and try to accelerate, the engine would not want to move, and it would start rocking the entire truck back and forth. and continue all the way up to third gear.

What I've done so far:
- Changed all spark plugs, spark plug wires
- changed the distributor cap and rotor

I've purchased a fuel filter which I'm going to install tomorrow. Not done that yet because all the times I've worked on it, the exhaust has been hot.

I'm not sure what else could be going on or wrong with my motor to cause this kind of thing to be happening. Any insight would be appreciated, thanks!

EDIT: Oct 12, 2014 13:40 PDT
So, today we replaced the fuel filter, it appeared I had water in there, so we put the new one in and put some HEET water remover in it. The truck seems to be operating a bit better now.
But it started to stall and bog down again, I went to AutoZone and purchased a new MAP sensor and made a vacuum tube for it; I haven't noticed any bad starts or stalling since I've changed it, but it is still having small amounts of surging below around 2k RPM, and still sort of hiccuping when I pull the throttle.

  • 1
    I would focus on the throttle body and around that area. Sounds like you TD dumping too much fuel. Maybe the throttle position sensor is bad or not reading correctly. Commented Oct 12, 2014 at 2:22

1 Answer 1


I essentially gave up and took it to a mechanic.
The fuel pump was dead.

What happened was my fuel pump was dying. It was providing around 5psi of pressure when it needed around 9-14psi. Overall, I had the mechanic replace the pump & regulator and the truck is working normally again. I had some codes on my computer for the EGR system and the MAP sensor. I replaced the MAP sensor and the vacuum tube myself;

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .