I have the same exact problem on my '93! Same engine, and a 4x4 as well. I just replaced the fuel pump (granted I must not have hooked it up right since my gas gauge isn't working), and that didn't seem to fix it. Tomorrow I'm going to swap the filter and hope that fixes it. If not, I'm going to clean the tank, and if that doesn't fix it I suppose I'll finally get around to fixing the check engine code for the circuit control failure that I have.


My rear differential is going out, I think. Could this be causing it? I don't know about OP but I only have this problem when I slow down at a ref light or stop sign or something.


Edit: after reading your other posts in this thread I'm pretty convinced we have the same problem. I've had a backfire that no **** sounded like a gun shot lol. After changing my pump today though, it still died, but it seemed to start right back up.

 

If you suspect the pump test the pressure! A tune up was done when(cap/rotor plugs wires)? Basic things first.

 

I replaced the coil a few years back - there was some aftermarket "performance" coil in there that really messed me up for a while. Best I can figure it was an intermittent short in the primary, so the only way I could get the thing to start was to insanely advance the timing (like to 25 degrees or something). I think the result of the short was that it radically increased the primary's charge time, which is why it needed the wild advance to build up enough field to generate a spark.

So although it's possible, I'm not thinking ignition this time around - the backfire when I step on it hard smells more like it's fuel-starved.

 

Well, I've been thinking about doing the pressure test. But it idles just fine - it's when it's really under load and I step on it that the problem occurs. Do you think that'd be reflected as low pressure at idle too?

 

Ah, interesting - didn't know those things are rebuildable. Rock shows two kits, though. I'm assuming there's no way to verify which pump it is until it's been pulled.

 

Hee!

It's easier to rebuild than to swap a soldered EEPROM on a PCM ... *grins*

(ISCET CET#LA-82, I know of which I speak there.)

RwP

 

So today in my '93 5.2, I ran a can of intake valve cleaner through it, and it doesn't but seem to be dying like before. I haven't driven it much yet because I gotta catch some sleep (I literally just did it, and gave it a short test drive). I'll give it a further test run tomorrow and let you know if that solved the problem for me. Couldn't hurt to try it in your '91.

 

the kits are For a 15 galln tank and a 21 gallon tank. Vin number will tell you which ome you habe or crawl under and look.

 

The pump is the same for the 15 and 22 gallon tank as it sits in the same spot on the tank. The 22 gallon tank has a lobe off the top of the back end of the tank. The pump goes in with the float arm lifting to the front of the truck or your gauge won't work. I expect the easiest way to find out is to look on Rock Auto for the pump for different gas tanks. I just looked the 3.9 and 5.2 pumps are the same they do not ask about the gas tank.

 

funny, everyone else does. And when I went to get my fuel pump replaced there was a 3 day wait. Guess why? Everywhere in town only had the 15 gallon pump. Rock auto is all but useless. I wish people would understand that. I honestly do not see the appeal of junkauto why everytbing thinks theyre the bees knees.