Hey everybody, I'm new to the forum. I just bought a 1998 Chevrolet pickup, 5.0, extended cab. When I bought it, the fuel pressure regulator was messed up and I have replaced it. That fixed a problem it had with starting when hot. Now, weeks later, I have noticed I can't get the truck to accelerate over 4000 rpm when I step on it (like when I'm passing someone). I thought it might be the catalytic converter being clogged but after removing it, the problem was still there. At 4000 rpm it seems like it's either misfiring or like there's a rev limiter. When I bought the truck, the gas guage was also a little erratic (moving like a hummingbird) but still showed how much gas I had. It ran all the way to 5000+rpm like it should, and this problem began before I replaced the fuel pressure regulator. Also the SES light did not come on when I removed the catalytic converter. I don't know if that has anything to do with my problem but I figured I'd mention it anyway. Thanks for all the help.

 

If the truck is high n miles i would replace plugs and wires just for peace of mind.does it shift good threw all gears.and check to see if there is a bulb where the dummy light is,they could have pulled it so buyer doesnt see probable faults.if you have a scanner you should be able to check for previous fault codes.good info my dad told me was when looking at a car to buy unplug the mass air harness or a plug wire while running that way sellers didnt try bypassing the warning lights.after doing that look in at the dash and a SES light should be on.he did that at a dealership once and caught them on it.

 

I agree - mine ran great for a week then started running rough after a week. Changed plugs and that fixed 'er right up. Can't go wrong changing plugs/wires/cap/rotor. Having just bought the truck (mine is also a '98 5.0) you just never know how well it was taken care of.

 

I replaced the plugs and wires the day after I bought the truck. They were still the originals, but didn't look too bad. I know for sure the warning light was not bypassed. I have seen it come on before when I unhooked a plug wire before I bought it (our family thinks alike). It does not have any codes as of now, though. It shifts perfectly fine through all the gears as long as I'm not getting it up to 4000 where it acts like it has a rev limiter and will stay in that gear for quite a few seconds (probably because it hasn't reached the predetermined shift point). The truck runs really strong all the way to 4000 but then it hits a wall.

 

sounds ALOT like a crank sensor to me.........just because it doesnt throw a code doesnt mean it aint bad...it could be just starting to go....but without a code it is hard to tell.....on a long shot a bad fuel filter or pump will do the same thing...it might be worth having the fuel preassure checked

 

i agree with last reply,i would try a new fuel filter first(cheapest).these newer cars and trucks shift off of the speedo so the faster you go while getting close to 4000 rpm will have some shifting issues.are you sure the plug wires are in correct order and plugs are gaped correctly.

 

So now I have an update on the problem. While driving, I can't get this thing to go over about 2800 rpm. This also happens when in park. I thought it was just a problem when under load since I never rev it up to anywhere near 4000 in park, but today when I noticed it is having problems at 2800, I figured I would try. So no matter what gear its in it does the same thing. I have already replaced the fuel filter and the plugs and plug wires are as they should be. I'm thinking it has something to do with the fuel pump. I'm not 100% though because I thought they either worked or didn't. I didn't think there would be a middle ground. So any suggestions?

 

as I said before have the fuel preassure checked and also check your timing (its computer controlled) but if the distributor was removed it could be in wrong and the computer wont beable to compensate

 

So I check this morning and it went up to 4500 (then I let off) without a problem. I think this problem is amplified when the gas goes to around a 1/4 tank. It seems to me that the fuel pump heats up and doesn't put out as much as it should. As long as I step on it within the first five or ten minutes of driving (and especially with a full tank) it doesn't have a problem. So does that sound close to being a likely cause? I'll get the fuel pressure checked soon.

 

that is very possible...it could also be the "sock" filter on the pump is clogging up when you get that low on fuel....sounds like a fuel tank r+r and possible cleaning needs to be done