'85 C4 Knock Issue
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Fuel level is thru a float thats on a sensor that is part of a fuel pump sender assembly.
You buy the whole assembly minus the pump. They can be had new for under $200 if you shop around.
I HOPE thats all this is....I've seen the FPR or Inj dump gas from shorting and know that to be extremely dangerous and deadly to the engine.... These fuel injectors are a different animal....do not assume anything here.
These are bank fired. Remember what I mentioned about ground path completion of circuits? Fuel inj are a great example. They are "hot" all the time. The ECM chooses when to ground them to fire. When they short out (and they do in many places) that causes the whole set to short and be stuck OPEN dumping tons of fuel into a cylinder where it washes the oil off everything and drains into the pan.
If thats happening it does not always smell of gas on the outside but the dipstick WILL stink of gas and the oil level will be wayyyyyy high.
If its only the gauge sending false signals...thats the best news there could be. Easy fix. There are tech write ups on pulling the assy out and cleaning the sender...
BTW, if you changed pumps, you didn't notice the float? ??????????????????????
You buy the whole assembly minus the pump. They can be had new for under $200 if you shop around.
I HOPE thats all this is....I've seen the FPR or Inj dump gas from shorting and know that to be extremely dangerous and deadly to the engine.... These fuel injectors are a different animal....do not assume anything here.
These are bank fired. Remember what I mentioned about ground path completion of circuits? Fuel inj are a great example. They are "hot" all the time. The ECM chooses when to ground them to fire. When they short out (and they do in many places) that causes the whole set to short and be stuck OPEN dumping tons of fuel into a cylinder where it washes the oil off everything and drains into the pan.
If thats happening it does not always smell of gas on the outside but the dipstick WILL stink of gas and the oil level will be wayyyyyy high.
If its only the gauge sending false signals...thats the best news there could be. Easy fix. There are tech write ups on pulling the assy out and cleaning the sender...
BTW, if you changed pumps, you didn't notice the float? ??????????????????????
Thread Starter
Intermediate
Joined: Jul 2012
Posts: 40
Likes: 0
Fuel level is thru a float thats on a sensor that is part of a fuel pump sender assembly.
You buy the whole assembly minus the pump. They can be had new for under $200 if you shop around.
I HOPE thats all this is....I've seen the FPR or Inj dump gas from shorting and know that to be extremely dangerous and deadly to the engine.... These fuel injectors are a different animal....do not assume anything here.
These are bank fired. Remember what I mentioned about ground path completion of circuits? Fuel inj are a great example. They are "hot" all the time. The ECM chooses when to ground them to fire. When they short out (and they do in many places) that causes the whole set to short and be stuck OPEN dumping tons of fuel into a cylinder where it washes the oil off everything and drains into the pan.
If thats happening it does not always smell of gas on the outside but the dipstick WILL stink of gas and the oil level will be wayyyyyy high.
If its only the gauge sending false signals...thats the best news there could be. Easy fix. There are tech write ups on pulling the assy out and cleaning the sender...
BTW, if you changed pumps, you didn't notice the float? ??????????????????????
You buy the whole assembly minus the pump. They can be had new for under $200 if you shop around.
I HOPE thats all this is....I've seen the FPR or Inj dump gas from shorting and know that to be extremely dangerous and deadly to the engine.... These fuel injectors are a different animal....do not assume anything here.
These are bank fired. Remember what I mentioned about ground path completion of circuits? Fuel inj are a great example. They are "hot" all the time. The ECM chooses when to ground them to fire. When they short out (and they do in many places) that causes the whole set to short and be stuck OPEN dumping tons of fuel into a cylinder where it washes the oil off everything and drains into the pan.
If thats happening it does not always smell of gas on the outside but the dipstick WILL stink of gas and the oil level will be wayyyyyy high.
If its only the gauge sending false signals...thats the best news there could be. Easy fix. There are tech write ups on pulling the assy out and cleaning the sender...
BTW, if you changed pumps, you didn't notice the float? ??????????????????????
He thinks its a bad sensor but I'll bust out my volt meter if I feel like taking the car apart and check it out.
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
While you are checking take a look at your harmonic balance. With age the old rubber will allow the outer ring to slip throwing timing way off. Did you use your CalPac (chip) when you changed the ECM? Are you sure you have the correct ECM? 85 ECM is unique to that year.
Long shots but worth a look.
The burned relay is the auxiliary fan relay. Shouldn't effect car running at all.
Burn Off Module is behind the Bread Box.
Long shots but worth a look.
The burned relay is the auxiliary fan relay. Shouldn't effect car running at all.
Burn Off Module is behind the Bread Box.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
Just pull the easiest spark plug to get at, and it it's not wet with gas, i'd go with the bad fuel sender.
Before you condemn the gas sender, go to O'Reilly's or Autozone and get some of the Chevron Techron additive. only use 1/4 of the bottle for 1/4 tank. It dissolves the contamination buildup on the wire wound rheostat in the gas gauge.
After about an hour, the gas gauge should work fine as long as it is submersed in fuel. The return fuel should keep things wet.
Be sure to rock the car after you put it in to mix it up. It will also clean your intake valves.
Before you condemn the gas sender, go to O'Reilly's or Autozone and get some of the Chevron Techron additive. only use 1/4 of the bottle for 1/4 tank. It dissolves the contamination buildup on the wire wound rheostat in the gas gauge.
After about an hour, the gas gauge should work fine as long as it is submersed in fuel. The return fuel should keep things wet.
Be sure to rock the car after you put it in to mix it up. It will also clean your intake valves.
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
You beat me to it...so I went out and looked again and I have no oil in the pan and I really don't think the injectors are stuck open. The car doesn't smell "gassy"
That being said, the car hasn't moved under it's own power in 8 months with the PO and 6 weeks with me, until last night. I've personally had the fuel pump and assembly out 3 different times, so it's entirely possible the gage is bad or the fuel level was not what I thought it was.
How is the fuel level calculated on the car? It's it a sensor or is it a float?
That being said, the car hasn't moved under it's own power in 8 months with the PO and 6 weeks with me, until last night. I've personally had the fuel pump and assembly out 3 different times, so it's entirely possible the gage is bad or the fuel level was not what I thought it was.
How is the fuel level calculated on the car? It's it a sensor or is it a float?
Thread Starter
Intermediate
Joined: Jul 2012
Posts: 40
Likes: 0
Just to give an update...The new MAF came in yesterday and that did the trick. She runs smooth as silk now. Finally got to take it out on a real drive. Had so much fun that my dad has now claimed the car as his driver..hahaha...it's ok i'll let him have his fun.
But now I want to find myself a c4
But now I want to find myself a c4
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
I don;t recall if I mentioned this when I was directing you to the MAF & relays, but whenever you have a similar problem keeping in mind that this engine is 100% computer controlled, BUT has a back-up program, you can FORCE it to run that program by simply unplugging the most critical sensor on the engine...the MAF.
Tha forces it to enter "LHM" or the stored program in the cal-pak or mem-cal. LHM is Limp Home Mode. It actually runs pretty well...with the SES on to let you know. If your SES is not on or coming on, verify that the bulb is good...that has baffled many folks that had issues but never saw a SES to tell them a code was available. Never trust that. Always check for codes by checking for stored codes !
Good luck,
Glad you got it going.
Tha forces it to enter "LHM" or the stored program in the cal-pak or mem-cal. LHM is Limp Home Mode. It actually runs pretty well...with the SES on to let you know. If your SES is not on or coming on, verify that the bulb is good...that has baffled many folks that had issues but never saw a SES to tell them a code was available. Never trust that. Always check for codes by checking for stored codes !
Good luck,
Glad you got it going.
