hey guys i bought my Fire-bird a while back its a 1986 2.8 v6 fuel injected, its recent after getting a tune up, liquid changes, and water pumps replaced, after starting the engine it'll stall out or run around 400-1000 sometimes it'll start at 1000 and burst to 1800 and than go down and fluctuate its all just recently(few days) started to show no rpms when i press on the gas pedal, ill turn it on and press the gas pedal and it'll go from like 900 rpms to nothing and sound like it wants to stall out,( it wouldn't drive over 15 mph i could hardly press the gas pedal or it would go to 0rpms) the engine light does turn on haven't checked the codes, but i gave the car to my mechanic to check out the engine light and look at it but i called him and he says its running fine now and it wasnt acting like it was for me, for him, and the engine light didnt show up he said. I thought maybe clogged catalytic converter or maybe a leak in a hose or maybe mass airflow or something(I'm somewhat new to cars) but he checked those and nothing i was also gonna check the fuel filter to see if its maybe clogged. any ideas on what might be the issue would be greatly appreciated

 

Hey, sounds like you may be on the right track with the fuel filter. Fuel pump may also be a possibility. Being that the filter is relatively inexpensive, rather easy to replace, and also a normal maintenance item, I would change that out if it has not been done within the last few years. Definitely check your fuel pressure when the symptoms appear for you to see if it is indeed an issue with the fuel system.

 

my fuel pressure was at a constant 35 with a lil fluctuating with higher revs but not much, and i was thinking could it be a Oxygen senor, my neighbor said it could be that cause i know i had from my caty back done on my exhaust so that ruled out the plugged caty but the sensors on the manifolds and the y pipes could they cause the weird things that are happening to my car? (the guides on autozone showed me like 4 different sensors on the system) should i change them all or is there a way to check and see if they went bad?

 

Dont start throwing parts at the car. That gets expensive and frustrating real fast. You probably do have a restricted fuel filter. You may also have a bad ground. I tend to think its a ground because there were no codes in the ECM. Any failure that would cause that loss of drivability should have set a hard fault code. Start the engine and let it idle while wiggling the wiring harness. The ECM grounds are on the passenger side rear of thew engine. Focus there and work your way around the engine bay. Another possibility is the ignition module in the distributor. They can get hot and fail, then cool down and work fine.

 

Its not a hard change I don't have to do anything special do i? for the fuel filter , i thought i might have cause its pressurized. the part is only 10 or 15$ at autozone

 

Fuel filter is fairly easy to replace. If your fuel system is indeed pressurized, simply pull the fuse for the fuel pump to render it inoperable. Then start the vehicle and let it idle until it "runs out of fuel"(due to the fuel pump not sending fuel). At that time the pressure should be relieved, but to double check you may place a rag over the shrader valve on the hard fuel line in the engine bay(where you check the pressure) and press the pin in the middle to release any remaining pressure. Keep in mind that if for some reason the pressure had NOT been released by the first procedure, it WILL be released by this one, so be aware that fuel may spray rather aggressively from the valve, hence the rag to help keep it contained. Once the pressure is relieved, it is simply a matter of locating the filter(mine is located at the rear of the vehicle just in front of the fuel tank). Use a box end wrench to hold to nut attached to the fuel filter stationary while using a second wrench to turn the nut on the fuel line so that nothing gets stressed or damaged. When installing the new filter, remember that it only flows fuel one way, so check the new filter for an indication of which way that would be. Once the new filter is installed, be sure to put that fuel pump fuse back in place, turn the key to on, not start, to allow the pump to pressurize the system and check your work for any fuel leaks. If there are no leaks you are good to start the engine.
Remember, as ASE doc said, don't just throw parts at the car. I only recommend the filter change because it is a normal maintenance item to begin with. Sensors get VERY expensive and also generally have testing procedures to rule them out as an issue. Same with the ignition module. So check those engine grounds, pick up a maintenance manual for you vehicle while you are at AutoZone getting the filter, and perform some tests that will cost you some time instead of more money. Hope this helps, good luck.

 

Another thought, I just reread your first post and you said that the engine light DID come on for you but it is now off. The trouble code may still be saved in the memory. You should still check for a trouble code even if the light is not currently on. It may point you in a new direction. Do you know the procedure for doing that without a scan tool? It's actually all over this forum, just do a quick search for "trouble code check", that should bring up the procedure, or check the tech articles link on the main page.

 

Im sorry. I didnt mean to say you shouldnt replace the fuel filter. The filter is a maintenance part anyway and inexpensive. Please do replace it. Verifying a clogged filter can be difficult anyway. I just dont want to see you start replacing sensors. The fact that your ECM didnt have any stored codes when checked tells me you may have a bad ground and that the ECM's memory may have been cleared by inadvertent loss of power. However, there are several failures that only set "soft codes" these codes may not remain in memory once the light goes out. It sometimes takes a few occurrences of a problem before a code will set and be retained. More likely though, as I said before, your ECM lost power due to a poor connection and the code was cleared.

Along with checking grounds, be sure to check fuses and their connections in the fuse panel as well.

 

before it was coming up with check engine lights but it hasn't turned on since which is really weird and its running better now after giving it to him and we didn't do anything i was gonna change the fuel filter anyways just in case really cheap part. i looked at the grounds coming from the engine to the walls and they seem fine a little discolored but nothing that looks like it would hinder anything in my opinion. and like i said before it the pressure was around 35 with a little bit of fluctuation, he never checked for codes because the car didnt show any or whatever he said. OH and my fuse box doesn't have any of the wording left on it does anyone know of where i can get the info for that and anything else on the car like schematics?

 

Its started to make an irratic noise in re engine its way different from what it should be doing it sounds like re engine has something rattleig in there its got an odd idle I rev it and trned it off and t went away? Could a piston be bad or all the cylinders not be firing properly? Man this car is endigup being an interestin buy...

 

Testing fuses on an older car can be interesting. Fords dont even have fuse ID, just numbers. You have to have a legend to ID the fuses. A quick easy test is just to check all fuses with a test light.

 

Was the noise while driving, under load, or at idle? Under load it may be spark ping or detonation. At idle it could be valve train, accessory drive, or timing chain. For those with 2.8 V6s, I mean no disrespect, but the 2.8 was not a good engine. At GM we had way too much trouble with them. After a few years GM dropped the 2.8 and switched to the 3.1 which was a similar design with improvements in some of the areas where the 2.8 had issues. Timing chain failure was common on the 2.8 as was valve train issues. Under hard use the OE crankshafts break fairly easy also. Sorry. As for wiring diagrams and service information, Formula 1XD mentioned a service manual at Autozone. They should have a Haynes or Chiltons which arent bad. If you plan on keeping the car, I recommend the factory shop manual from Helms Publishing.

 

ya it was making the noise while it was idleing but it doesnt do it all the time only every once in a while and if i turn it off and back on it usually goes away, but someitmes it'll start fine and drive fine but kick up rpms, and while driving it feels and sounds like its kicking or something i feel a small jerk, it just had a tune up a little while back along with a water pump change.

 

You want to pinpoint the noise. Use an inexpensive mechanic's stethescope you can buy at the parts store. Find where the noise is loudest. Either in the timing cover or a valve cover. You may have a low oil pressure issue at idle thats allowing a valve lifter to collapse.(Is the noise more prevalent when the engine is hot?) If the noise is louder in the timing cover, its probably a failed timing chain tensioner.

 

I have an 87 Firebird with same engine and it had the MFI until we found out that the genius who took the engine apart to rebuild it had put the spark plug wires to the wrong cylinders as well as put the distributor in 180 degrees backwards. That was my problem with starting the car and the rpms being all over the place. I did have a problem with the fuel pump getting the wrong amount of voltage as well and that caused it to burn out and it aided in some of the problems as well. Once we carb'd it and got rid of the MFI, it runs smooth and purs like a kitten with no rpm problems.

 

well it only makes the strange idle when i turn it on sometimes, but usually i can just turn it off and and start it up again and it'll be gone, i've never run it long enough to get it to full or its optimal heating to see if it'll stay that long. but i changed the fuel filter and i daw that the idling screw was missing so i got that a junk yard. it seems to run a little smoother but it still has the strange bursts of energy ethier when i just start it up or when im driving or pulling up to a stop is when it usually decides to do that. Could it not be getting enough gas to the engine? I'm gonna try as ASE said and pin point it but its so erratic that it might be a challenge just to find the highest point.