hesitation around 1500 rpm, fuel pump/filter?

[boosh71]

Hoping someone might be able to help with this issue. Basically what happens is I'll be at a stop light or stop sign idling and when I take off there is a hesitation around 1500 rpm. It's more pronounced when there is a load on the truck (such as running the A/C or towing). I thought it was the fuel pump failing but a local auto parts store indicated that when those fail the truck will not get any fuel at all. I'm going to replace the fuel filter in a few minutes and also clean the air filter. A couple times it even died on me when taking off from a dead stop. Any ideas? Could it still be the pump?

Thanks guys!

[boosh71]

I just replaced the fuel filter and cleaned the air filter. No improvement. Any ideas?

[jro909]

if its a 5.3 somebody recommended new wires and plugs on here to me, i have the same problem but its only after the first initial shift from 1st to second when cold, the engine rides 1500 rpms and just goes blank, i lose a little power and then all the sudden it shifts and runs fine..the engine dosen't misfire or stumble its just like the engine forgets what its doing

[bigbob6988]

Can you give us a rundown of you truck? You didn't give any details in your post.

[boosh71]

Sorry guys, what was I thinking? It's a 1994 GMC K1500 5.7L TBI 268,000 miles on it. The last tune up I did was at least two years ago, maybe three. Back then I replaced all the plugs, wires, distributor cap, and rotor.

[JeffsJeep04]

Sounds kind of like a fuel pressure regulator to me, especially since you already did the usual suspects (fuel filter and air filter). Generally when it stumbles then catches back up, it's a fuel or air issue in my experience. When it stutters under load at any RPM, that's usually when I'll start digging into the ignition system.

[ibeholden12]

I have a 97 siverado i just did the pump on today truck stumbles hard on accelaration from take off and climbs out of it at 1st shift could this be regulator or firing,( cap,rotor)

[boosh71]

Sounds kind of like a fuel pressure regulator to me, especially since you already did the usual suspects (fuel filter and air filter). Generally when it stumbles then catches back up, it's a fuel or air issue in my experience. When it stutters under load at any RPM, that's usually when I'll start digging into the ignition system.

I'll have to check in to that, is this a common problem?

[JeffsJeep04]

Fairly. I sold a bunch of them when I was working the parts counter. I know my dad had a very similar issue to yours on his NBS Z71 and the FPR cleared it right up.

[boosh71]

Fairly. I sold a bunch of them when I was working the parts counter. I know my dad had a very similar issue to yours on his NBS Z71 and the FPR cleared it right up.

Thanks, is it located in the throttle body?

[JeffsJeep04]

Drivers side fuel rail, about half way back is where it's at on the NBS trucks. Really simple replacement job. Half hour and some needle nose pliers.

[bigbob6988]

Drivers side fuel rail, about half way back is where it's at on the NBS trucks. Really simple replacement job. Half hour and some needle nose pliers.

He has an OBS TBI truck without fuel rails. The FPR is actually part of the throttle body injection unit. Sooo... most likely that is not his problem, but still could be...

[jro909]

will this problem throw a light on the dash on NBS?

[boosh71]

Well guys, here's an update. I've replaced the fuel filter, cleaned the air filter, and just replaced the fuel pump and screen. Still a hesitation between 1000-2000 rpm. Is the engine just tired? I just want my truck to run like it should be! I usually tow quads to the dunes or the mountains but lately haven't really been able to because the power just isn't there. I mean I could still tow, but when I hit any hills I drop down to like 38 mph! Any Ideas?

[NEUMANNZZ]

check compression to find out.

[toomanyballs]

is it cold or when the engine is warmed up?

[boosh71]

is it cold or when the engine is warmed up?

Both when it is cold and warmed up. To be sure I'll warm it up before I leave for work tomorrow.

[JeffsJeep04]

Fuel pressure regulator...still sounds like the issue to me.

[boosh71]

Well guys I found the problem. The timing was off 9 degrees! It runs so much better now! Thanks for all the help.