86 X19 fuel pump..

T

TajMan

True Classic
My yellow car would have hot-start trouble sometimes in the past. With my delicate working of the throttle, I'd always get it to start anyway even when hot.

My buddy was borrowing the car recently. He told me he couldn't start it today, I figured I would start it fine once I got there.

When I arrived, it wouldn't fire at all on its own, BUT it would off starter fluid..

I can only assume the fuel pump has gone bad (86 FI X).

I'll check it out tomorrow, I don't even know if there is a schrader valve on the fuel rail to see if it has pressure like it should, or if I need to take the feed line off the fuel rail and check that way.

Pump should activate for a sec when the key is turned to acc, and when the engine is cranking?

RockAuto has the best deal for $112, bosch unit..
 
Following the debug procedures in the guide for fuel injection would be a good path to success.

Yes, generally the pump should run immediately upon the engine rotating and causing the flap in the AFM to move. The switch under the black cover of the AFM can be tweaked and cleaned if needed assuming that is the issue.

Then flap may be jammed and won't open, thus the switch never closes.

Try to minimize using starting fluid, its not the best for the engine.
 
Troubleshoot...

Troubleshoot using the guide. The pump, wiring, filter, AFM switch, relay, coil signal wire... any could be the problem.

FYI the doesn't (shouldn't) run with the key only turned to "on", but rather only if the engine is running or the starter is turning.
 
Its not the coil signal wire, car fires ok off starter fluid (I know its no good to do that too much to the engine).
I'll follow the diagnosis steps, thanks
 
TajMan said:
Its not the coil signal wire, car fires ok off starter fluid (I know its no good to do that too much to the engine).
I'll follow the diagnosis steps, thanks
Click to expand...
Greg is referring to the wire that goes from the coil primary to the ECU. This wire is ease to knock loose, and if it not connected you'll still get spark but the injectors never fire. See this post for photos.
 
Coil primary - ECU wire was still connected.
I wasn't getting fuel pumping out of the pump at all.
I hate to say, I replaced the fuel pump with a new ($80), but I am STILL not getting anything pumping out of it when cranking! :(
I was pretty sure the old pump must have just finally given up after the age and the time car had been sitting previously.. guess not.
Where is the fuel pump relay located exactly (by fuses), and can I swap out that relay with a different one I have here to test with?

(I assume these relays are different from my '79 Carb'd X I have laying here)
 
You can test the fuel pump independent of any vehicle system, just unplug the electrical leads from the car's harness and using some sort of 12v power source, apply 12v pos and neg to the spade connectors sticking out of the pump, the spade connectors have + and - signs next to them.

If the pump works with independent power, your issue is in the FI system or vehicle harness. If the pump does not work with independent power, then the pump is bad.
 
The Bosch FI dual or double relay is in the spare tire compartment, mounted to the panel between the spare tire compartment and the fuel tank compartment.

IMG_1943.jpg
[/URL][/IMG]
 
Obviously I don't need to test fuel pump itself with 12V to figure if pumps are good I think they are,
I can assume that old pump was probably good (I'll test later) and new pump is probably good (most likely, and even more likely now that the fact car STILL doesn't start, with nothing else changed).

I'll check spare tire well and see if I can find relay, this yellow car has a custom box w/ 10" speaker behind the pass. seat where the spare tire should go..
 
Don't assume...

Assuming may lead to frustration. If it were me, I'd verify that the pump works before moving on. Use a fused 12v power source and tickle the pump (+) terminal, the (-) is always (or should be) grounded. If this doesn't work, test the ground next. If these tests show the pump is good then start looking at the wiring and controls. Also check polarity, pump will run backwards if the wires are on the wrong terminals, and the car won't run that way.

Fuel pumps, like other parts, can be bad right out of the box.

Also, check the fuse. Top right fuse (G) in the panel. Should be 10A (red).
 
Top right fuse in the panel, marked I.E.? Its a 10A I have there, and its good.

I got the fuel pump polarity right, I checked that before I installed the new pump purple neg green pos.

Those wires to the fuel pump are not getting the voltage they are supposed to when cranking, I'm seeing at max 1V not 12.

I located the relays in the spare tire compartment, but what/how do I need to go about testing now?
 
How can proper operation of the fuel pump be 100% verified?

What is the age of that Bosch fuel pump, is it clogged with goooo from bad fuel, rust from the tank, and much more.

All this must be verified 100% proper operation before looking else where or the root of the grief will never be resolved.


Bernice


TajMan said:
Obviously I don't need to test fuel pump itself with 12V to figure if pumps are good I think they are,
I can assume that old pump was probably good (I'll test later) and new pump is probably good (most likely, and even more likely now that the fact car STILL doesn't start, with nothing else changed).

I'll check spare tire well and see if I can find relay, this yellow car has a custom box w/ 10" speaker behind the pass. seat where the spare tire should go..
Click to expand...
 
haha you're giving me the grief! I had been driving the car for some time regularly! And it has a brand new pump installed now!
I'm testing the voltage at the pump, it is not being provided.
If I can fix that problem, and then the engine still isn't starting, then of course I'd go from there..

pardon my ignorance?,
all that is listed in that link, are poor quality images of old wiring diagrams from a manual.

So it seems the 'relay set' (fuel pump relay?) is the Bosch unit behind the pass. seat with 5 wires from one plug and 7 terminals on the other plug?
I checked the 7-pin plug the pins are numbered. Could anyone point me in the direction of what pins I can test for +12V (with the key off, and with the key cranking) to try and diagnose a possible bad relay? Thank you much
 
Last edited:
Diagnosis help...

1v at the pump when cranking suggests the dual relay contacts are bad. Do you have another you can swap in? Alternatively you can jumper the fuel pump relay to provide power to the pump all the time, as a way of diagnosing the problem. I wouldn't leave it that way for safety reasons.

Connect 88d (power to fuel pump) to 86c (key on power).
 
New pump as in brand new, or new to your car? What brand / model , etc?
The green wire at the pump comes from that double relay - add a jumper from a 12v source (one of the pink wires I believe. Check with a test light) then see if it pumps fuel.
 
New does not mean known good or properly functional.

Connect a volt meter across the fuel pump electrical terminals. Leave the ground wire from the fuel pump to ground in place. Connect a wire directly from the battery or known good source of 12volts directly to the fuel pump, check the volt meter reading, check fuel pressure.

If the fuel pump is operating properly with these test conditions, check the dual relay. Possible the contacts are a problem or drive to the relay is a problem.


Bernice
 
I don't think anyone has mentioned, here's how you can test quite easily.

Remove the filter side hose of the AFM, turn the key to the "run" position, fuel pump will not run in this mode.

Stick your finger in the AFM and push on the flap, the fuel pump will start. If not, you've got to chase down why. If you hear the pump run, then check pressure.


My car also doesn't start hot - removing the power side of the combo relay, then cranking until it runs and dies, then reconnect and it fires up. I suspect my injectors are bad and leaking when hot/under pressure.
 
You must log in or register to reply here.
Back
Top