1985 fuel injectors hold 30 at idle, 38 with fpr removed, go to zero in 5 seconds
11-05-2015, 07:30 PM
#1
Oil Producer
Thread Starter
1985 fuel injectors hold 30 at idle, 38 with fpr removed, go to zero in 5 seconds
aklim, here you go, some more fodder for you.
its this 1985 and i am desperately awaiting my scanner cable.
its got a bad idle. it goes like stink and kicks the crap out of my 87 when its out and about. but dies at idle.
checked for vac leaks, none.
checked for fuel pressure...ding ding ding...
turn key on: goes to 40 then goes to 0 as soon as pump turns off.
running: at 30. it does go up when i stomp on it.
pull vac to fpr when on, goes to 40, returns to 30 when vac repalced.
turn off car: insta loss of pressure down to zero.
i have read fore the 85, 30 is the correct pressure at idle.
pump can supply plenty of pressure when called for.
given the above plus:
a, my exhaust burns my eyes and reaks and makes my clothes smell
b, when in introduce air to the car by creating a vacum leak, the car runs better, not with a higher idle, but with a more steady idle,
c, fpr checks out, no gas smell.
this is souinding like a rich condition. am i right here?
loss of pressure when pump turns off means either i have a pump check valve that is blown OR fuel squirting out somewhere between pump and injectors (don't have)....or...ding ding ding...an extremely leaky injector.
The issue with teh leaky injector is that the car starts fine every time. so its not like the injector floods it so bad that it won't start.
thoughts? can't wait till i get the aldl cable. i am expecting to see high fuel trims or whatever they are called in obd1 (int and blm?). even though i cant find a vac leak.
its this 1985 and i am desperately awaiting my scanner cable.
its got a bad idle. it goes like stink and kicks the crap out of my 87 when its out and about. but dies at idle.
checked for vac leaks, none.
checked for fuel pressure...ding ding ding...
turn key on: goes to 40 then goes to 0 as soon as pump turns off.
running: at 30. it does go up when i stomp on it.
pull vac to fpr when on, goes to 40, returns to 30 when vac repalced.
turn off car: insta loss of pressure down to zero.
i have read fore the 85, 30 is the correct pressure at idle.
pump can supply plenty of pressure when called for.
given the above plus:
a, my exhaust burns my eyes and reaks and makes my clothes smell
b, when in introduce air to the car by creating a vacum leak, the car runs better, not with a higher idle, but with a more steady idle,
c, fpr checks out, no gas smell.
this is souinding like a rich condition. am i right here?
loss of pressure when pump turns off means either i have a pump check valve that is blown OR fuel squirting out somewhere between pump and injectors (don't have)....or...ding ding ding...an extremely leaky injector.
The issue with teh leaky injector is that the car starts fine every time. so its not like the injector floods it so bad that it won't start.
thoughts? can't wait till i get the aldl cable. i am expecting to see high fuel trims or whatever they are called in obd1 (int and blm?). even though i cant find a vac leak.
Last edited by VikingTrad3r; 11-05-2015 at 08:18 PM.
11-05-2015, 08:41 PM
#2
Le Mans Master
My money is on the check valve. 85 fuel pressure should be about 36-39 with vacuum hose to regulator removed and plugged.
••••• TESTING FOR LOSS OF FUEL PRESSURE
... Here are the sure fail tests for the fuel system to save you time and money.. Take a fuel pressure gauge attach it to the Schrader valve.. Turn the key on and off a few times to build up the pressure in the system... If you are having starting trouble the pressure will probably drop as soon as it hits 38 or 40 and the pump turns off it will probably leak back to zero within a few minutes. Ok now right after you prime the system pinch off the return line near the tank if the pressure drop stops it is a bad fuel pressure regulator.... Next pinch off the feed line if the pressure holds then the leak is before the point where you pinched the line IE fuel pump check valve..hole in the metal line on the sending unit caused by it rubbing on the inside of the tank you should visibly be able to see this if you pull the pump and the sending unit...(this was my problem) or the pulse dampener which is the piece between the pump and metal line on the sending unit.. the diaphragm tears.. and last if you pinch both the feed and return line near the tank and the leak down of the pressure continues then a fuel injector is your problem.. This is the GM test.. saves time and money..
•• disconnect the vacuum line from fuel pressure regulator
••••• TESTING FOR LOSS OF FUEL PRESSURE
... Here are the sure fail tests for the fuel system to save you time and money.. Take a fuel pressure gauge attach it to the Schrader valve.. Turn the key on and off a few times to build up the pressure in the system... If you are having starting trouble the pressure will probably drop as soon as it hits 38 or 40 and the pump turns off it will probably leak back to zero within a few minutes. Ok now right after you prime the system pinch off the return line near the tank if the pressure drop stops it is a bad fuel pressure regulator.... Next pinch off the feed line if the pressure holds then the leak is before the point where you pinched the line IE fuel pump check valve..hole in the metal line on the sending unit caused by it rubbing on the inside of the tank you should visibly be able to see this if you pull the pump and the sending unit...(this was my problem) or the pulse dampener which is the piece between the pump and metal line on the sending unit.. the diaphragm tears.. and last if you pinch both the feed and return line near the tank and the leak down of the pressure continues then a fuel injector is your problem.. This is the GM test.. saves time and money..
•• disconnect the vacuum line from fuel pressure regulator
11-05-2015, 08:48 PM
#3
11-05-2015, 09:00 PM
#5
Oil Producer
Thread Starter
it does have a cold start yes.
guys, i am going out tonight to test this. Mrs. VikingTrad3r can operate the key to prime the pump.
Thnx!
guys, i am going out tonight to test this. Mrs. VikingTrad3r can operate the key to prime the pump.
Thnx!
11-05-2015, 09:23 PM
#6
Melting Slicks
Hi
My 85 runs at around 30 to 34 psi in standard form, that is because the 85 runs 24lb injectors. When I first got my 85 I was wondering why others had 36 to 38 psi, its because of the 85 24 lb injectors.
I know with my adjustable fuel pressure regulator 45 to 48 psi is the sweet spot for better mid and top end performance, however it will idle very very rich.
The high hydrocarbons is what stings your eyes, it has no effect on idle quality just the eye stinging.
The fuel pressure drop can be due to the fuel pump not holding pressure or the pulse damper split. it can affect startup however if you turn the ignition on a second or two before cranking it will start right up. Your injectors could be leaking down.
before I changed the Multec injectors to Bosch 3 injectors, I had the same fuel pressure drop when I turned of the engine.
Now the pressure stays at the pressure I set the fpr to.
Good luck
My 85 runs at around 30 to 34 psi in standard form, that is because the 85 runs 24lb injectors. When I first got my 85 I was wondering why others had 36 to 38 psi, its because of the 85 24 lb injectors.
I know with my adjustable fuel pressure regulator 45 to 48 psi is the sweet spot for better mid and top end performance, however it will idle very very rich.
The high hydrocarbons is what stings your eyes, it has no effect on idle quality just the eye stinging.
The fuel pressure drop can be due to the fuel pump not holding pressure or the pulse damper split. it can affect startup however if you turn the ignition on a second or two before cranking it will start right up. Your injectors could be leaking down.
before I changed the Multec injectors to Bosch 3 injectors, I had the same fuel pressure drop when I turned of the engine.
Now the pressure stays at the pressure I set the fpr to.
Good luck
11-05-2015, 09:55 PM
#7
Oil Producer
Thread Starter
Thnx gerard. going to do the return and pickup line pressure test now. that should give me more info. ill report back
Hi
My 85 runs at around 30 to 34 psi in standard form, that is because the 85 runs 24lb injectors. When I first got my 85 I was wondering why others had 36 to 38 psi, its because of the 85 24 lb injectors.
I know with my adjustable fuel pressure regulator 45 to 48 psi is the sweet spot for better mid and top end performance, however it will idle very very rich.
The high hydrocarbons is what stings your eyes, it has no effect on idle quality just the eye stinging.
The fuel pressure drop can be due to the fuel pump not holding pressure or the pulse damper split. it can affect startup however if you turn the ignition on a second or two before cranking it will start right up. Your injectors could be leaking down.
before I changed the Multec injectors to Bosch 3 injectors, I had the same fuel pressure drop when I turned of the engine.
Now the pressure stays at the pressure I set the fpr to.
Good luck
My 85 runs at around 30 to 34 psi in standard form, that is because the 85 runs 24lb injectors. When I first got my 85 I was wondering why others had 36 to 38 psi, its because of the 85 24 lb injectors.
I know with my adjustable fuel pressure regulator 45 to 48 psi is the sweet spot for better mid and top end performance, however it will idle very very rich.
The high hydrocarbons is what stings your eyes, it has no effect on idle quality just the eye stinging.
The fuel pressure drop can be due to the fuel pump not holding pressure or the pulse damper split. it can affect startup however if you turn the ignition on a second or two before cranking it will start right up. Your injectors could be leaking down.
before I changed the Multec injectors to Bosch 3 injectors, I had the same fuel pressure drop when I turned of the engine.
Now the pressure stays at the pressure I set the fpr to.
Good luck
11-05-2015, 10:52 PM
#8
Le Mans Master
If you determine that thru the testing it is likely the fuel pump. Then you have to pull the pump. And gerardvg is correct, it could be the pump or the pulsator could be partially off the fuel line. If you change the pump delete the pulsator and use the rubber tube that is usually supplied with a new pump.
11-05-2015, 11:11 PM
#9
Oil Producer
Thread Starter
If you determine that thru the testing it is likely the fuel pump. Then you have to pull the pump. And gerardvg is correct, it could be the pump or the pulsator could be partially off the fuel line. If you change the pump delete the pulsator and use the rubber tube that is usually supplied with a new pump.
Next question is then, do i really need to change this like asap?? I am hell bent on chasing this crap idle issue with this car and i think this rules out leaky injectors doesn't it? Sounds like it is more than likey the check valve.
If it is the pulsator, will that ruin anything? I don't know what a pulsator is sorry.
next on the list of things to check before my scanner arrives, are the plugs, wires, rotors, timing, coolant system pressure leakdown test (i think i am going to fail this one....dun dun DUNNNN...)
11-05-2015, 11:17 PM
#10
the pulsater just connects the pump to the fuel line like a hammer connector for water to keep pipes from banging and replaced with just a hose that can be in fuel. but if it leaks bad enough you will not have enough pressure to run.
Last edited by antfarmer2; 11-05-2015 at 11:20 PM.
11-05-2015, 11:21 PM
#11
Oil Producer
Thread Starter
thx for help. onto the next thing. i will one day replace the pump but its not a1 priority.
11-06-2015, 09:19 AM
#13
Oil Producer
Thread Starter
crap, did i say return?
whoops, i pinched the sending line not the return line.
pressure appears to be bleeding back through the sending line. sorry.
pressure appears to be bleeding back through the sending line. sorry.
11-06-2015, 12:55 PM
#14
Le Mans Master
If it is bleeding back thru the sending line, they it is the pump, pulsator or other issue.
Replacing the pump is a hour job at the most. Remove the fuel door, remove the rubber dam around the filler neck, remove the rubber lines (mark which goes were) and unplug the electrical feed. Then remove the 8 bolts (number from memory) and gently lift out the unit.
Remove filter sock at base of pump, remove pump, remove pulsator. Install new pump. Replace pulsator with hose and two screw clamps. Add new filter sock to base of pump. Slip unit back in tank......tighten bolts, hook up electrical and hoses. Install rubber dam and fuel door.
I have changed a couple now and have it down to 1/2 hour.
Replacing the pump is a hour job at the most. Remove the fuel door, remove the rubber dam around the filler neck, remove the rubber lines (mark which goes were) and unplug the electrical feed. Then remove the 8 bolts (number from memory) and gently lift out the unit.
Remove filter sock at base of pump, remove pump, remove pulsator. Install new pump. Replace pulsator with hose and two screw clamps. Add new filter sock to base of pump. Slip unit back in tank......tighten bolts, hook up electrical and hoses. Install rubber dam and fuel door.
I have changed a couple now and have it down to 1/2 hour.
11-06-2015, 01:05 PM
#15
Oil Producer
Thread Starter
i will replace it soon. but for now, i want to dial in on the crap idle. now that i have verified the injectors are not bleeding out, i can move from the fuel system to something else. agreed pump should be swapped but its not the pump causing bad idle.
cheers and thanks for helping verify !
If it is bleeding back thru the sending line, they it is the pump, pulsator or other issue.
Replacing the pump is a hour job at the most. Remove the fuel door, remove the rubber dam around the filler neck, remove the rubber lines (mark which goes were) and unplug the electrical feed. Then remove the 8 bolts (number from memory) and gently lift out the unit.
Remove filter sock at base of pump, remove pump, remove pulsator. Install new pump. Replace pulsator with hose and two screw clamps. Add new filter sock to base of pump. Slip unit back in tank......tighten bolts, hook up electrical and hoses. Install rubber dam and fuel door.
I have changed a couple now and have it down to 1/2 hour.
Replacing the pump is a hour job at the most. Remove the fuel door, remove the rubber dam around the filler neck, remove the rubber lines (mark which goes were) and unplug the electrical feed. Then remove the 8 bolts (number from memory) and gently lift out the unit.
Remove filter sock at base of pump, remove pump, remove pulsator. Install new pump. Replace pulsator with hose and two screw clamps. Add new filter sock to base of pump. Slip unit back in tank......tighten bolts, hook up electrical and hoses. Install rubber dam and fuel door.
I have changed a couple now and have it down to 1/2 hour.
11-06-2015, 11:41 PM
#16
Race Director
11-07-2015, 12:17 PM
#17
Team Owner
How about just buying a Racetronix setup and be done with it since you traced it to the circuit from the return line at the tank to the FPR, injectors, etc to the fuel sock in the tank? If you want to go cheap, try the hose but you might be pulling out the pump again.
11-07-2015, 12:18 PM
#18
Team Owner
i will replace it soon. but for now, i want to dial in on the crap idle. now that i have verified the injectors are not bleeding out, i can move from the fuel system to something else. agreed pump should be swapped but its not the pump causing bad idle.
cheers and thanks for helping verify !
11-07-2015, 01:01 PM
#19
Oil Producer
Thread Starter
hahahahahahaha. Ak u have a real hate on for multecs! Ive seen you say exactly this like a thousand times.
My injectors are black. multecs were like a beige color right?
Anyway, i am quite sure i have a leaking intake gasket, so i will pull the fuel rail, take detailed pics of injectors, and send to jon at fic and go from there for either cleaning or replacement. love jons vid demonstrations.
thanks Ak!
My injectors are black. multecs were like a beige color right?
Anyway, i am quite sure i have a leaking intake gasket, so i will pull the fuel rail, take detailed pics of injectors, and send to jon at fic and go from there for either cleaning or replacement. love jons vid demonstrations.
thanks Ak!
No, you verified the injectors are not bleeding out but you haven't verified the injectors are good yet. Check with FIC if they are Multecs. If they are NOT, send them to FIC for cleaning and testing. If they are, send them to the trash can and buy a reman set from FIC and send it back to them every few years for cleaning and testing.
11-07-2015, 03:28 PM
#20
Team Owner
hahahahahahaha. Ak u have a real hate on for multecs! Ive seen you say exactly this like a thousand times.
My injectors are black. multecs were like a beige color right?
Anyway, i am quite sure i have a leaking intake gasket, so i will pull the fuel rail, take detailed pics of injectors, and send to jon at fic and go from there for either cleaning or replacement. love jons vid demonstrations.
thanks Ak!
My injectors are black. multecs were like a beige color right?
Anyway, i am quite sure i have a leaking intake gasket, so i will pull the fuel rail, take detailed pics of injectors, and send to jon at fic and go from there for either cleaning or replacement. love jons vid demonstrations.
thanks Ak!
Last edited by aklim; 11-08-2015 at 10:10 PM.