Hello all, I am new to posting here but have read countless threads. Cant seem to find a similar problem to what I am having so I'm hoping for some help.

I recently picked up a 1986 Fiero that was stored in a garage since 1999. 2.5 4cyl with 5 speed manual. Brought it home, sprayed some ether in the TBI and it fired right up. I've gone through and replaced fuel pump, filter, TPS, MAP, IAC, PCV, cap, rotor, plugs, wires, ignition coil, temp sensor, took apart the TBI and rebuilt it. Also replaced every fuel line, brake lines, rotors, calipers, E-brake cables, pads, bearings, shocks, struts, ball joints, clutch line, master and slave cylinder, and many other mechanical components and cosmetics that don't relate to my problem.

My issue is that I took it out for about a 100 mile ride and everything was fine except that it overheated when I was almost home. I have to still flush the cooling system but I'm waiting for the replacement radiator to be delivered. Now my problem happened after it overheated, so I was wondering if there is a sensor I'm overlooking that triggered and never reset? My issue is that the car starts just fine and will idle around 900RPM nice and smooth. As soon as I release the clutch is seems as if it is starving for fuel even if I work the pedal and try to keep the RPM wound up. The EGR seems to be fine, the plunger is nice and smooth. Fuel pressure is more than enough when I hook up the tester. I've checked the vacuum lines and haven't found any leaks. I even removed the catalytic converter and put in a straight pipe thinking it was plugged up but nothing changed. I'm at a loss what could be wrong. I was thinking maybe the charcoal canister is dirty, but when I remove the hose going to the TBI and plug it nothing changes. (EDIT) I forgot to mention that I checked the timing and it was slightly off so I set it to 8 degrees. I also forgot to mention the it is still throwing code 34 and 35 even after replacing the IAC valve.

Any help would be greatly appreciated, or just steer me to a post I may have overlooked. Thank you all so much.

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2007 Dutchmen motorhome, 30ft, Chevy 6.0
1992 GMC Sierra stepside, 350 5speed, 2wd, no options but A/C
1984 Tire Melting Chevy S-10, short box, small cab, base model no options, Stroked SB Chevy, 5 speed Muncie
1972 Chevelle Malibu, numbers matching, rare Carolina Blue double dash vin tag. All original near mint.
1986 Pontiac Fiero Base model, 2.5 L-4(for now) 5 speed, all new brake pads, rotors, bearings, calipers, clutch master and slave, copper line front to back, brake lines, fittings, valves front to back, fuel pump, sending unit, epoxy coated fuel tank, copper/nickel fuel lines, filter, rebuilt TBI, much much more....

[This message has been edited by osrclint74 (edited 09-29-2021).]

Welcome to the forum!

quote Originally posted by osrclint74: I checked the timing and it was slightly off so I set it to 8 degrees.

Was the timing done with the ALDL jumper in place?

Yes I put the jumper in then started the car(after it had already been warmed up). I checked #1 and it was bouncing between 4 and 12 BTDC. Then checked #4 and it was right at 8. I tried moving the distributor a degree or two in either direction and tried moving up and down the driveway but still no luck. I did turn the car off and remove the jumper before i restarted and tried moving it each time. I'm wondering if the injector is bad? It seems to have a nice atomized spray at idle and it definitely dumps more fuel if I'm in the engine compartment working the throttle by hand, but maybe it's plugged up just enough to affect it?

Did you replace all of those parts before the problem, or after?

Does it rev up okay if you are in neutral?
(Maybe there is something in the drivetrain that is not wanting to rotate freely)

Advance the timing and see what happens. Don't let it knock.

I replaced all the parts listed before I had this problem except the TPS and MAP, and IAC because the trouble codes were for all 3 of those. I tried putting in the old parts and still have the same issue. Yes I did have a jumper wire in when I did the timing. I tried advancing it about 2 degrees at a time then trying to drive it with no improvement. The tab only goes up to 16 degrees BTDC and I advanced it to what would probably be about 35 degrees before it would start chugging, tried retarding it as well but still no luck. There is nothing in the drivetrain that seems to be bogging it down at all. It revs up fine with the clutch pushed in and i can feather the clutch to keep the rpm wound up to about 3500 and get it to move normal but as soon as i fully engage the clutch it loses all power. I'm at a total loss. I did notice that when checking the timing that #1 cylinder and #4 do not match which I assume is normal. I added the two numbers, divided by 2 then set the #1 cylinder timing, that's what I read. Am I timing it wrong? Is it possible the timing belt jumped? It seems like it is normal. I would hate to have to remove everything to replace the timing belt but that may be my next option. I was hoping to just beat on the 4 cylinder then do the V8 swap, but after all the stuff that's been bought for the engine I feel like it would be a waste of money to pull the motor now. Any ideas what I should check next? Thanks in advance for any replies.

The L4 Fiero actually has timing gears, so you'll never have to worry about a belt jumping a tooth.

My first thought when you say it's falling flat on acceleration is that it's likely either a fuel or a timing issue.

I didn't see anywhere that you said you had codes, but I'm responding on a phone while I wait. If there are no codes, then it's probably just a timing issue. Even as an L4, acceleration should be a little snappy... but you shouldn't expect a strong pull or anything at any real RPMs... but it shouldn't fall flat.

Yes it does have timing gears, I just checked what's available on Rock Auto and they only have gears, no belt so I'm assuming the timing didn't jump. When I replaced the fuel pump and all the lines and filter I checked the pressure and it was 12psi if I remember correctly. I was thinking maybe the fuel injector is slightly clogged but the engine has no problem revving to 5000 in neutral and the spray looks plenty atomized. I'd hate to waste $50 on a new injector if I don't need it but I'm at a loss for what else my issue might be. Maybe I need a new distributor? I already replaced the cap, rotor, plugs, wires, and ignition coil.

Could it possibly be low compression? I'll check the cylinders this week when I get my tester back. The oil doesn't seem watered down with fuel, a little dirty but still seems normal. I ordered a new fuel injector, should be here monday or tuesday. After I replace that, I am at a complete loss except for maybe low compression.