ITSWILL

iTrader: (12)

Well my car wont start unless i pour some gas down the intake after the intercooler then it starts and i can shut it off and then turn it on but then if i leave it off for too long i cant start it up again. Some one told me it could be the fuel pressure regulator bleeding off too much pressure. Right now im broke as a joke, and cant afford a fuel pressure tester does anyone know of a "ghetto" way to test this. And when i do get a tester does anyone know what pressure i should be looking at?

1988 Turbo II

ITSWILL

iTrader: (12)

i found part of my answer kinda?

fuel pressure should be between 64 and 85.3 psi b4 the regulator and it should be 34.1-39.8 after it.

ITSWILL

iTrader: (12)

i read the fsm and i still dont see how i am supposeed to even test the pressure after the regulator.

The regulator is hooked directly to the fuel rail right?

HAILERS

There is a Circuit Opening Relay that causes the fuel pump to come on/work.

It has two coils that have the potential to pull the relay in.

One coil works to pull the relay in, and make the pump work, when the key is HELD to Start. Hold the key to Start and the fuel pump runs and the rail has pressure.

The other way(s) the Circuit Opening Relay pulls in, is if a ground is put on the OTHER coil inside the Circuit Opening Relay. The vane on a series four afm is what puts the ground on that coil mentioned. IF the vane of the afm is moved about a 1/8" or so aft, a internal switch *makes* and put a ground on the Circuit Opening Relay's OTHER coil, which then makes the fuel pump run.

A third way of making the pump run, is to jumper the Fuel Pump Check connector in the engine bay. Yellow in color, two sockets and near the boost/pressure sensor. Jumpering its two sockects together puts a gnd on the Circuit Opening Relay just like the switch in the afm does. IF the key is to ON, the pump runs continuously.

All the bs above means this. I think for some reason, when you put the key to START, that signal is NOT pulling the Circuit Opening Relay in and therefore not causing the fuel pump to run and pressurize the fuel rail. So. To prove me wrong, all you have to do, is go to the fuel pump check connector and jumper it. Key to ON. Now try to start the engine. Don't pour gas in the intake when doing this.

IF now, the engine starts as a normal car, then you need to find out why the Circuit Opening Relay isn't getting the start signal from the key switch.

Your problem could be something totally different. Got me.

The FPR being bad is a very slim possibility. Very low on the pecking order. Jumper the fuel pump check connector and it'll stay pressurized all the time the key is ON or better.

ITSWILL

iTrader: (12)

Thanks for your help, but unfortunately the jumper thing doesn't work, it makes fuel pump when the ignition switch is on or cranking but the car doesn't start.

As for the fuel pressure regulator, as unlikely as it is to fail it does make sense.

the other thing i thought could be the problem would be that the injectors weren't firing, so i back probed the ecu on the primary injector pins and connected them to ground, i could hear them open but this still didn't make the engine start.

I appreciate your help as always

HAILERS

The FPR is the last thing in the fuel rail before the fuel is sent back to the tank thru the return line.

When the pump is ON, the fuel pressure in the rail is around 37-39psi if the engine isn't running. When the engine starts and idles, the pressure falls to around 28-32psi (vacuum being pulled on the FPR at idle).

If you deadhead the fuel pump pressure, the pressure will be the high figures you mentioned above.

Usually fuel pressure will stay pressurized in the rail after the key is put to off, for close to thirty minutes. There's a check valve in the fuel pump. But even if it bleeds off right after the key is to OFF, when you go to START the next time, the rail is pressurized in less than three seconds (been there, seen that on a fuel gauge).

You say you can start the engine if you pour some fuel in the intake. But if you turn it off, it won't start if you leave the car for a prolonged period of time.

The question I have is this. If you get it started and let it FULLY warm up, will the engine start the next few times you try to start it? LIke fully warm it up....turn it off. Start it within a few minutes. And be able to do this numerous times and it starts each time as long as the engine is hot.

Or is what is happening.......you pour fuel in the intake. It starts up. Engine gets warmed up. Turn it off and it starts the next time you try. Turn it off. Leave it for several hours and come back and it won't start. As in the engine is now not hot but cool to cold.??????

The ECU has a START map that does NOT use the afm signal for fuel during start. It uses the waterthermo sensor on the water pump. MOre fuel is injected when the water is cold. Less when the engine is HOT. IF the sensor is disconnected, the ECU defaults to a HOT temp. So if the engine is actually cold, not enough fuel will be delivered.....because the ECU is seeing 179*F temp and not enough fuel is injected.

Or if the ECU never sees the START signal from the ignition, then the START map is never used and the ECU uses the afm for the fuel amount which will not be enough fuel for starting if the engine is cold.

So I'm saying, if the engine starts each time when the enigne is hot/warm, and not when the engine is cold, the above MIGHT be your problem.

RETed

Dunno where you got this from, but they are totally wrong.


-Ted

ITSWILL

iTrader: (12)

I have replaced the thermo sensor (the one behind the thermostat neck in the really crappy spot to get to), but that didn't change anything. I can pour fuel into then it will start. I can turn it off and immediately turn it back on. But if i leave it alone for a while (could be 5 minutes for all i know) it will not start on its own. I could check the wiring to the thermo sensor but i kind of doubt that it the problem. Also sometimes it will die while it is running and then it wont start either.

Also what is "dead heading" i read the fsm and still am not sure how i should test the fuel pressure.

ITSWILL

iTrader: (12)

I got those numbers from the factory service manual
page 4a-67

Am i not looking at the right thing?

Do you have any ideas what the problem could be?

I would appreciate any ideas.

ITSWILL

iTrader: (12)

The FSM says that the thermo sensor goes to pin 2I on the control unit but i cant quite tell where the other wore is going, (the AFM maybe?).

Ranzo

If you suspect the regulator is the problem then you can take some pliers, they make plier specifically for this kind of operation but anything can work, Take those pliers and crimp or block off the return line. This is the deadhead I think Hailers is talking about.

That will nearly stop any fuel from returning to the tank thereby causing your fuel pressure to go to its maximum even if the regulator is broken. The car should start at this point if the regulator is the problem.

Your other alternative is to go down to Auto Zone or wherever and buy a fuel pressure gauge and T in the fitting in the supply side hose and screw the gauge on the schrader valve. that will allow you to see what the pressure is. Costs about 40 bux best I remember.

ITSWILL

iTrader: (12)

thanks fro the advice ill try crimping that return line

I can block it anywhere right ?

ITSWILL

iTrader: (12)

crimped the fuel return line and no change so I guess i can assume the fuel pressure reg is working.

ITSWILL

iTrader: (12)

Ill try testing continuity of the thermo sensor wires tomorrow.

Feel free to put out any other ideas.

HAILERS

Oh. It's a green/white wire in 2I. The other end goes to ground. But it's a round about way to ground. All the sensors gnd wires are spliced together and end up at pin 2C. So if you were to ohm it out, you'd pull the middle plug off and put the meter leads on 2C and 2I.

A really better method is to put the meter lead to a known gnd, like the studs that hold the ECU bracket on the chassis. The with ALL plugs on the ECU, backprobe the 2I with the meter on dcvolts. IF the key is ON and the engine is fully hot, it will read something like a half volt or b/t 0.4 and 0.5 vdc. In that area if the engine is HOT. If the engine is cold, it depends on how cold is cold. Usually it'll read b/t 2vdc and 3vdc when cold.

IF the voltage is somewhere close to zip, then go to the water thermosensor plug and pull it off. Look inside the plug and see if one of the two contacts is pushed back inside the plug. Sometimes they won't lock in the plug and when you offer the plug up to the jack on the sensor, the wire that isn't locked in will push back and not make contact. Much like the problems with the BAC plug. Socket pushed back.

YOu could use a piece of wire bare at each end and stick it in the back of 2I and the other end touching the meter lead in order to probe 2I. Like pull the middle plug off so you can access the 2I easier.......stick the wire up the back of 2I and then carefully reinstall the middle plug without pulling the wire out of the back of 2I.

ITSWILL

iTrader: (12)

thanks for the advice but im not quite sure where you are going with this. What do you suggest i do with the other end of the wire? check continuity? run it to my sensor? check voltage? Or are you just trying to give me some advise on back probing. I have found that a paper clip works really well for back probing.

Its kinda shitty out today but ill let you know what I find as soon as i get a chance

Thanks again

RETed

Idle fuel rail pressure should be about 35psi to 40psi.
The fuel pump "dead head" pressure can go up to about 90psi.

I think you read the numbers right, but you got the corresponding specs wrong.


-Ted

ITSWILL

iTrader: (12)

thanks for the clarification

HAILERS

I'm suggesting that instead of checking for continuity of the sensor or the resistance of the sensor, that you check the voltage input from the sensor at pin 2I using a paper clip as you described. Meter neg lead to a known ground and the positive lead of the meter to the paper clip. Key to ON. ON a cold engine the temp would be somewhere b/t 2-3 vdc. Fully hot engine it'll be a half volt. IF you see anything like those figures then the sensor is connected up and working. If you see zip volts or over five volts, something is connected up wrong. Just probe it and tell us what the voltage was on 2I.

The deadheading was meant to describe how you would put a gauge on the output line of the fuel filter. The outlet would go nowhere other than to the gauge. The pressure would be the high figure in the FSM. What??? 70-80 psi or something like that. I didn't take time to look.

To look at the fuel rail pressure, you TEE into the line off the filter. The fuel is still going to the rail and the excess pressure in the rail is bled off by the FPR and sent back to the fuel tank. Fuel flows constantly. The pressure in the rail is determined by how much vacuum or pressure the intake manifold is applying to the FPR's vacuum port. More vacuum, like at idle, less pressure in the rail. Less vacuum or actual pressure on the FPR's *vacuum* line means more pressure in the fuel rail.

I'm just guessing what MIGHT be wrong with your starting problem. In some ways it sounds like not enough fuel being delivered by the fuel injectors during Start. The amount of fuel during Start is determined by a internal fuel map inside the ECU and that amount is determined by the water thermo sensors input to the ECU, the RPM's being under 500 and the ECU actually seeing the Start signal from the ignition switch.

Your problem might be something totally different. What? Got me. Maybe a large air leak?

IF you can get it started and the engine fully warmed up, then turn it off and restart it fine in the next ten/fifteen minutes or so, but not be able to start it after the engine cools down, say after an hour, then what I suggested MIGHT be the problem.

ITSWILL

iTrader: (12)

ok i got 3.01 volts. Any ideas?

ITSWILL

iTrader: (12)

thanks hailers ill check that stuff out

ITSWILL

iTrader: (12)

I found a problem.

First off I thought that the start map was initialized by solely by the water thermo sensor. I wasn't understanding that there is another wire that goes to pin 3b on the ecu.

I checked 3b while cranking and sure enough it just stayed at about 1.4 volts so i ran a wire from the starter relay to pin 3b. now it is seeing about 9.5 volts when cranking but it still wont start.

Anyway, I just thought i would give a little update.

PS. I am now realizing that HAILERS told me about that signal a bunch of times. I hope you dont feel like i was wasting your time, as you led me to learn a lot about my car and i appreciate your help.