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wierd engine sputter

88k5blazin

88k5blazin

1/2 ton status
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clark new jersey
Got an 88 k5 350 tbi stock except for dual exhaust. Even after it has warmed up and I go to take off in first gear the engine won't rev up and it bogs down for a few seconds then it takes off and then is perfectly fine for a while then randomly it will do the same thing when taking off again. Have replace o2, coolant sens. Fuel filter. And throttle position sens. Has newer plugs and wires. Engine ran better then ever until this problem started. It has a very minor flucutating idle that bothers me more then effects drivability. I'm anal nbout stupid little things like that. Its not throwing any codes either. Thanks in advance
 
Almost sounds like the problem I had in my 88 last summer. Turned out to be the fuel pump. On my case I changed the pump and screen in the tank and problem solved.
 
Just replaced that bout a year ago. Not saying that couldn't be the problem cause there's always bad apples in the bunch but what would cause it to rendomly sputter only when taking off
 
no check engine light?

I just recently had an issue where i lost fuel pressure, ran like crap, didn't want to move real well, thought it was somthing else cause i was SURE it wasn't the pump, as i had just replaced that a year or so back.

Finally put the pressure gauge kit on the lines and sure enough, low pressure. Removed everything, pulled the pump assembly out and turns out the little hose piece that connects the pump to the hard line on the pump assembly, had a small slit in the hose. Not sure how it happened, but i replaced everything anyways cause it was all apart, and has been good since.

First time i have ever seen the hose fail on a pump setup.
 
4xcrazy said:
no check engine light?

I just recently had an issue where i lost fuel pressure, ran like crap, didn't want to move real well, thought it was somthing else cause i was SURE it wasn't the pump, as i had just replaced that a year or so back.

Finally put the pressure gauge kit on the lines and sure enough, low pressure. Removed everything, pulled the pump assembly out and turns out the little hose piece that connects the pump to the hard line on the pump assembly, had a small slit in the hose. Not sure how it happened, but i replaced everything anyways cause it was all apart, and has been good since.

First time i have ever seen the hose fail on a pump setup.
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what should i be looking for in pressure and can i check it from the line by the fuel filter or does it have to be by the TBI unit?
 
the kit i have replaces the fuel filter, pull the filter out, install this adapter, run the pump or motor for a short time till you get the reading on the gauge. As for pressure, i believe it was around 12-15psi.

When i had my recent issue, if i remember, the pressure was about 3-5psi, hardly moved the gauge, so yes, something as stupid as a small slice in the hose, can create a serious issue.
 
I got $10 on the egr valve. Take the vacuum line off that goes to it and plug it. See what happens. Its a free try.
 
y5mgisi said:
I got $10 on the egr valve. Take the vacuum line off that goes to it and plug it. See what happens. Its a free try.
Click to expand...
if i pull the line off what should happen? will it run perfectly fine? if that is the problem do i just replace the egr valve and problem solved? its worth a shot before i spend any more money
 
y5mgisi said:
I got $10 on the egr valve. Take the vacuum line off that goes to it and plug it. See what happens. Its a free try.
Click to expand...

the problem i ran into when doing vacuum line checks, is i got around to pulling a line off the MAP sensor, when i did this, the engine smoothed out and ran good for some reason, so i thought maybe it was bad, bought a new one,, no change after install,,, the other thing i did was remove the gas cap, sounds weird, but i was trying everything, i removed the cap to see if i could hear the pump making the normal, or any abnormal noises.

I left the cap off, and when i went to restart the motor, it wouldn't take, would not fire.

From what i gather, there was some pressure still in the tank, assisting the pump at getting fuel to the motor to run somewhat, but when i released the pressure from the tank, the pump, with the hole in the hose could not get the fuel to the TBI.

NOW, with all of this being said, i AM NOT telling you your fuel pump is bad, i am just giving you an idea for something else to check. From my experience so far with these TBI's, the most common problem seems to always be fuel delivery related.

Kinda why i was asking if the CEL came on at all, as soon as i had this issue, the light came on, obviously reading a lean condition, which is what happened in the past when the fuel pump itself died.
 
Nah it never came on. Def somwthing I'm gonna check though since I did replace the pump awhile ago. It ran good for awhile but them the sputter started and its been all down hill since then
 
and btw, if you check the pressure at the fuel filter, replace it, might as well since it's already off.

When WAS the last time you changed the fuel filter, anyways...
 
The pump and filter have maybe 200 miles on them I don't get to drive it nearly as much as I'd like to. Last time I had a rough idle a few years ago I changed the filter and it ran great after that
 
Yep. Should run totally normal, just with no sputter. That was the problem on my 90 with a tbi 350. go to take off gently from a stop light and would spoutter and try to die. same thing backing out of the drive way.
 
I just chased a bad egr valve for over a month... Mine was sticking, so I thought it was working. It would hesitate pulling out easy from redlights, and trying to parallel park would almost stall in reverse. Don't forget there's an egr solenoid in-line just before the egr valve, disconnect the vacuum line just before the solenoid. I think it's much more common for the egr valve to go bad than the solenoid, but anythings possible in a 20+ year old truck... I think cfm industries sells a neat adapter kit for a permanent fuel pressure guage that mount right to the throttle body that was pretty cheap.
 
I'm thinkin its not the EGR valve. I disconnected the hoses and it is still doing it. Now if I give it gas and hold at 2000 or so rpm then hit it with more cause it sputters and almost dies. Hopefully my buddy will show up with his fuel pressure tester today.
 
Hang in there, it was really frustrating getting mine to run "perfect", but well worth it, I've gained 5 mpg average from when I started, and it runs and drives so much better... The downside is my wife likes to drive it now...
 
Disconnecting the EGR vacuum hoses does not eliminate it from the system. If the EGR valve is bad it can still let exhaust gas flow into the intake under some or all conditions. Which is why it can be a pain to diagnose.

I took some 1/8th steel and cut it in the shape of the EGR gasket and drilled 2 holes for the bolts to go through. Sealed it with some Ultra Copper RTV sealer. Essentially made my own block off plate. Truck runs a whole lot better now. Eventually I will replace it with a new one, including the vac switch, but right now it's not in the cards. Check engine light comes on sometimes, usually when cruising down the highway. Stays on till I shut the truck off then it's off till the next time I'm cruising.
 
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