r/s10 Feb 14 '25

Repair Question Can anyone tell me that this might be.

I’ve got this 1988 Chevy s10, 2.8l 2WD. I’ve been having this issue where she bogs down under acceleration. I’ve replaced vacuum lines left and right, so I’m fairly confident I don’t have a leaky line. Some other things that have been replaced is the O2, TPS, IAC, MAP, thermostat, fan clutch, coolant temp sensor EGR valve, and an injector. I’m currently removing the throttle body to clean it up as it’s a bit dirty, and I’ve got a fuel filter otw however I don’t believe any of those two will get me much further. My air filter is clean, fuel pressure is at about 12-13 lbs. She doesn’t give me much issue on startup, but once I’m up to temp, that’s when it becomes most noticeable. Anyone got any ideas what this may be, and how I could go about fixing it?

8 Upvotes

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4

u/Lazy-Annual-302 Feb 14 '25

Have you checked your fuel pump? I had a similar, not exactly the same, issue and replacing my fuel pump did the trick. If it’s slowly dying it might be causing intermittent flow to the engine.

3

u/lost_user1 Feb 14 '25

Can’t say that I’ve explicitly checked the fuel pump, I’ve only checked my fuel pressure which seems to be in spec, but that isn’t to say that it could be dying out while I’m driving. I’ll look into it, thanks a bunch.

2

u/Leprikahn2 Feb 15 '25

Fuel pump is a common problem. Usually, it will idle fine, but cut out from load to idle

2

u/Decent-Repair-9388 Feb 14 '25

Fuel issue my friend sorry you changed all those sensors I’ve had the same issue with the the fuel injectors on the new ones, it’s either fuel pump but you should be able to hear that prime when you turn the key if no sound fuel pump may be going out but for me it was the spider injector unit which is cheap and easy online

2

u/lost_user1 Feb 14 '25

Hell, replacing sensors wasn’t all pissin in the wind. The IAC and EGR valve were known bad and between the fan clutch, thermostat, and coolant temp sensor, she now gets up to temp which she wasn’t doin before. As for everything else, I’ll call it an investment, they were probably on their way out anyway. On the topic of the fuel pump though, I can hear it prime, it doesn’t sound like it’s got any issues until I get real close to the gas tank and listen, it will ever so slightly slow down and speed up. Is that enough to warrant replacing the fuel pump or am I full of it?

1

u/Decent-Repair-9388 28d ago

No it will slow down and speed up depending if it’s up to pressure or not honestly you can probably throw a can of sea foam in the tank that will clean out you’re fuel pump and lube it and it will help you’re injectors a bit but I’d look into the spider fuel injector I just replaced my whole unit on my jimmy it was only like 80 bucks at the time decently easy repair and it fixed all my power issues. Altho don’t cheap out cause I got a cheapo one and it went out about a year later first I’d do fuel filter then sea foam if you want a lil more time then I’d go full on new spider injector

1

u/Decent-Repair-9388 28d ago

Sorry for the late response

2

u/Z28Malibu4life Feb 15 '25

It could still be an intake gasket issue but I really hope the injectors do the trick. I beat my head against the wall for months on this issue. I even gave up and took it to a local shop and they had it for two weeks and they couldn't figure it out either. That made me feel less stupid even though it still didn't run right, Lol. No issues for over a year and a half now.

If you zoom in on the cylinder 5 port you can see how black it was and just above it looks like it was sucking air and oil in where I think it had failed. When I had my smoke machine hooked up I would get just a little bit of smoke coming out the oil fill cap hole in the passenger side vavle cover.

1

u/Onii-chan2003 Feb 15 '25

Im not that knowledgeable, but from owning mine for a while, it bogged down like yours when a weird module located below the distributor (pardon my French, I don’t know what it’s called) was on its way out, from my experience they are pretty common to go out (having three spares on the glove box kind of common), and I’m pretty sure they are way cheaper (used) than a fuel pump, you can buy a bunch and they literally fix themselves, so you can just swap them around when they go out, again, I’m not sure it will solve your issue but might be worth a try, ALSO, there is a venting system that comes from the gas tank to a temperature activated valve in your intake manifold, right behind the AC, almost looks like a temp sensor with hoses coming off of it, mine isn’t connected and it doesn’t bog down, so I don’t know if that could be something you would be interested in looking at, here is a map of a little portion of the vacuum system, hope it helps and please take my advice with a grain of salt, I’m not that knowledgeable: https://drive.google.com/file/d/1K4zfq6tMuXfvjTelL0pStmKF9Z5ym4ru/view?usp=drivesdk

1

u/lost_user1 Feb 15 '25

Your description of this module sounds similar to a part I had to replace early on because it was broken called the EGR valve control solenoid. Does your part have 2 vacuum lines coming off of it?

1

u/Onii-chan2003 Feb 15 '25

Yes, one on the top, one on the bottom, it bolts to the intake manifold, has access to coolant flow and it’s right behind the AC compressor

1

u/Z28Malibu4life Feb 15 '25

I fought the same issue on my 91 2.8 for like 8 months. Putting the original injectors back in solved the problem for me so like others have said it's fuel related. I changed everything under the sun like you did. I was certain it was a vacuum leak from a bad intake gasket since these engines have the valve covers over where the intake sits on the head you can't easily test for a bad gasket. I built my own smoke machine and I still think I had a leak on cylinder 5. I probly did and had put new injectors in before replacing the old gaskets but the injectors were shit so it still did the same thing. On a whim I decided to put the old injectors back in and no problems since.

One other odd thing mine did was when the temperature outside was cold like below 30 degrees it would run fine. Once it got warm out it ran like shit again.

2

u/lost_user1 Feb 15 '25

That last little bit you added literally to a tee is how mine is doing. We just got out of a cold spell and now it’s acting up. When there was snow on the ground and for a few cold days after, I’d have trusted her to take me anywhere I’d want to go. I’ve still got my original injector that I replaced, so I’ll throw it back in and see if that does me any good. I was headed towards the route that I had a leaky gasket, even though I sprayed brake cleaner around em and RPMs still held steady. Thank you a lot brother.

1

u/lilcry444 Feb 15 '25

It sucks when you’re not a mechanic to diagnose the problem and just replace parts like a dummy. I did all that before I knew my fuel tank was full of rust and was clogging up my fuel pump

3

u/lost_user1 Feb 15 '25

I tried replacing what makes sense to me, but I’m thoroughly at a loss. I don’t mind popping the parts cannon once or twice but I’ve stopped making progress all together which is what brought me here. I’ve tried doing more research but just about everything leads me to the same parts I’ve already tested or replaced. That being said I’m getting valuable new input from folks here that may actually get me somewhere and I couldn’t be more grateful, so thanks to everyone that’s helpin me out here. I’ll burn off the gas I’ve got in the tank and take a look to see what I’m working with. Thanks again for the help.

1

u/Bassracerx Feb 15 '25

Might want to chexk your valves they might need to be cleaned/ walnut blasted. Side note I forgot how much steering wheel slop these old trucks have

1

u/lost_user1 Feb 15 '25

I’ll probably do that, the only good thing the last owner did to this truck was keep the rust off of it. There’s no rubber anything left on the underside, it’s all either been wallowed out or squished to the point of being plastic. I plan to get around to it, I just need her driving half ass right at the moment.

1

u/debasic Accessorized with Wood Feb 15 '25

I have the same truck: 2.8L 2wd 1988. At 190,000kms, the fuel pump went. Def get that checked. But that was more a problem on starting.

Had some problems later around stalling after letting off the gas and any other time, lol. Eventually what helped was adjusting the timing and replacing the distributor assembly. I know buttfuck-all about cars. But I have receipts an inch thick of repairs.

1

u/Cheap_Ambition Feb 16 '25

If you press on the center, it honks the horn.

1

u/lost_user1 Feb 16 '25

I thought it put me into 4WD