For the last month or so, my 1989 S-10 has been intermittently been acting like it is running out of gas. It has a TBI 2.5 Liter Iron Puke engine. I have replaced the fuel pump, fuel filter, module, coil, cap, rotor, plugs and wires. I have also tried a different MAP sensor. No luck. Anyway, it will drive normally and all of the sudden, it wil start bucking and losing power substantially. I will have to finally pull over. The truck will idle roughly and then die. If I try to drive it, it does not have enough power to move the vehicle. I occasionally get a Service Engine light and comes up as a O2 sensor code which I recently replaced. It will usually start right back up, run, then die. The EGR valve will move if I suck on the hose, so it doesn't seem to be sticking. I also checked the resistance on the injector and it is similar to a new one. Tapping on the ECM has no effect. If I stomp on the gas when it is doing this at idle, it will bog and die. What is wrong?

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1992 Camaro Z28; Engine:383 w/Edelbrock RPM ported heads. Lunati Solid Roller Cam 224/232 .502/.502, Fluidampr, 1.5 Roller rockers, 30 lb injectors. Haltech E6GM DFI, SLP 1 3/4" headers, 4" Mufflex, T56, 4.10. Super Ram.

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Definition:

NOPI: n. 1. import 2. Sticker worth 47 hp 3. import with 6" exhaust tip
antonym: smallblock

 

I knew someone with GM's 2.5 front-wheel-drive TBI motor... she had a poor driveability problem, and the car always wanted to stall. Turned out the diaphragm (sp) in the fuel pressure regulator was shot, and was leaking. The mechanic replaced just the diaphragm.. I guess it's a service item? She didn't know how he checked it; I assume with a fuel pressure gauge.

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

That or TPS possibly.


Definately take a fuel pressure gauge to it Tho, Should help you Narrow it down.




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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype

 

I've had the same problem with both of my 4.3 S-10's. I know you've already done it but, Consider changing your fuel filter again.

What happens is you get a bad load of gas and a piece of garbage gets into your filter somehow. That same piece gets to the filter clogs and your enginge starves for fuel. When the pressure is no longer holding said garbage in the filter opening it backs through the system and allows the engine to run again. You'll also want to try to dilute the fuel in the tank with good quality gas in case it is a bad tank.

The filter is only a few $ and it is concievable that it's still the problem. I've had both of these things happen to me so I know how frustrating it can be. In either event your describing a fuel problem, have you checked the pump relay? Just thought of that.

Hope it helps

 

I have a cavalier beater that does a similar thing. I found out that it was actually the auto trans. The solenoid inside the trans that downshifts when you slow down was getting stuck. Thus causing it to remain in 3rd while slowing to a stop. If you have driven a manual trans, you know what happens next. The car starts making a huge vibration, and eventually stalls out.

 

I have an 2.5 in my 86 Cutlass Ciera. I had a problem sorta like this back a few years ago. What would happen is, all of a sudden the car would buck like it was going to stall, and then die. It would start right up, run and then do it again. This problem would come and go and really not set a code. I had it checked and evidently, oil was leaking from the distributer shaft and getting on my something that controled my spark. I forgot the name of it. They fixed the leak and replaced the "spark module?" and it has given me nothing but pleasure since. I do seem to replace coolant temp sensors every so often, but that is about it.

Your 2.5 may not have a distibutor so, this may just be food for thought.

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89 Formula 305 TBI
160* stat, 200* fan switch, K&N, Headers, 3in Flowmaster (hollow cat) back, pullies, 1.6 full roller rockers, B&M trans cooler, home-made ram-air
3.73 Richmond gears and SLP Zexel Torsen Posi (waiting for install)

 

The truck has a manual trans, so I can rule out the auto trans problem. The distributor and module were clean when I replaced the cap, rotor, and module. I haven't checked the fuel pressure regulator yet, but if the diaphram was torn, wouldn't it do this at all times? Yesterday it started fine, I drove it for around 20 minutes on the highway and it starts losing power bad, and I am now going 40 while everyone swerves around me at 80 during rush hour. Not good. Stepping on the pedal only makes it worse. Where can I tap a fuel pressure gauge? This morning it would hardly start and had no power until I drove it for a few miles, bucking with every gear change. Its hard to predict it is so intermittant, but seems to happen at least once everytime I drive now. Would a bad injector do this?. It doesn't seem to be temperature dependent.

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1992 Camaro Z28; Engine:383 w/Edelbrock RPM ported heads. Lunati Solid Roller Cam 224/232 .502/.502, Fluidampr, 1.5 Roller rockers, 30 lb injectors. Haltech E6GM DFI, SLP 1 3/4" headers, 4" Mufflex, T56, 4.10. Super Ram.

Double-Pump This! EFI Rules!

Definition:

NOPI: n. 1. import 2. Sticker worth 47 hp 3. import with 6" exhaust tip
antonym: smallblock

 

BTT

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1992 Camaro Z28; Engine:383 w/Ported Edelbrock RPM heads. Lunati Solid Roller Cam 224/232 .502/.502, Fluidampr, Comp Cams 1.5 Roller rockers and lifters, Comp Cams Triple Valvesprings, SVO 30 lb injectors. Holley/Walro 255 lph in-tank pump, Haltech E6GM DFI, SLP 1 3/4" headers, 4" Mufflex, T56, 4.10. Super Ram. 17" X 9.5" Ronal FireHawk Rims w/ 275 40ZR17 Bridgestone RE 730's up front and Nitto Drag NT 555R's out back.

Double-Pump This! EFI Rules!

 

Could it be a clogged up catalytic converter? I would think that would make it act up all the time, but, it's worth checking out.

 

One other thing to check may be the coolant temperature sensor, or the wiring to it. It actually should set a code if this is the problem, but it won't always.

Even though your ecm has passed the "tap test" that doesn't mean it is definately not the problem.


Another thing I suggest would be to check the ecm grounds. They should be connected to the back or top of the head, or one of the bell-housing bolts.

Good Luck!



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Working on:
'84 Z28 LG4 305 with 200,000 original miles!
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350 (ZZ430)
using primarily GMPP parts.
Short block sitting on a stand. (Man, those Fast-Burn heads sitting on it look good!)

Starting to look like the Kicker poster child!

ASE Certified Master Tech

 

I just finally figured out a similiar problem on my 92 RS V6. It would idle fine then after 10 minutes of driving down to 40mph and no power finally dying and never restarting. After replacing countless parts, finally took it to the shop and had them put it on the computer. Problem was injectors 1 is basically dumping fuel and the others aren't so great either. So if you have already done cap, plugs, rotor.... basics check the injectors I would say they could cause that kind of problem

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85 POS
92 RS

 

To answer all of your problelms, just put a 305 in it! You'll love the torque this small engine can make in a light weight vehicle! U can get a 305 pretty cheap too.
njdaewoo

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86 Tramaro 90% Trans Am/ 10% IROC/Z (nose, hood,& fenders)
Trans Am Mods as of 1/10/01
3inch
T.E.S/Flowmaster setup,gutted cat,gutted maf,relocated mat,373 gears,upgraded factory chip,255 liter h/press. walpro f/pump & throttle body coolant bypass
njdaewoo@excite.com

 

Thanks guys. I checked the fuel pressure regulator and it was fine too. I don't think it is the cat either since it is intermittent. The last two places I have are the injector and/or the ecm. I guess it could be the pick-up coil in the distributor also. It feels like a fuel problem though. One more thing to add, it seems to run better with Heet in the tank. I've been through 10+ tanks of gas since it started happening so i'm sure it's not moisture or water in the tank, but will Heet free up an injector for a while?

Concerning the 305, I have a 50,000 mile 305 out of my Z28 `and a set of super comp headers just waiting. I have neither the time or money to do it right now. But ohhh is it tempting. If I did it, I would have to change the trans, the rearend gear, and I'd like to keep it fuel injected for economy and driveability.

Thanks, keep it coming, I will not let the truck die. I have 20,000 miles to go until 200,000.

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1992 Camaro Z28; Engine:383 w/Ported Edelbrock RPM heads. Lunati Solid Roller Cam 224/232 .502/.502, Fluidampr, Comp Cams 1.5 Roller rockers and lifters, Comp Cams Triple Valvesprings, SVO 30 lb injectors. Holley/Walbro 255 lph in-tank pump, Haltech E6GM DFI, SLP 1 3/4" headers, 4" Mufflex, T56, 4.10. Super Ram. 17" X 9.5" Ronal FireHawk Rims w/ 275 40ZR17 Bridgestone RE 730's up front and Nitto Drag NT 555R's out back.

Double-Pump This! EFI Rules!