87 Turbo - Fuel Pump and Relay not powering on

[rayfordmachen]

I've searched through the forums several times trying to pick up a tip that might give me an idea what to try next.

 

I have an 87 Turbo that wouldn't start. Fuel pump not running. No voltage to fuel pump. Looked at relays. I didn't really determine which relay was for the fuel pump but I did find the one for the blower and swapped each of the other relays into the blower relay socket and each one powered on the blower fine. There were four relays up on a higher bracket and two relays lower down and just directly above the ECU which I take from reading the forums one of those is the fuel pump relay.

 

I can run wires directly from the battery to the fuel pump and it runs fine.

Hooking up the green test wires and turning ignition on starts a box at the front right clicking but the fuel pump doesn't cycle or power at all as I've read it should cycle during this test?

 

Codes:

33 Vehicle Speed Sensor (VSS) or circuit

34 EGR solenoid valve stuck on or off

35 Purge control solenoid or circuit

42 Idle switch or circuit

 

Could any of these codes actually keep the ECU from powering the relay on for the fuel pump or maybe provide a clue?

 

Thanks in advance if anyone can point me in the right direction.

[rayfordmachen]

Also,

I noticed that even though the speedometer works, the cruise control doesn't. Does each one gets it's speed signal from a different place? Would the sensor that feeds the cruise control also be the one that gives the code 33 Vehicle Speed Sensor (VSS) or circuit? But could that being bad cause the ECU to not turn on the fuel pump?

Thanks.

[cd45]

My 87 non turbo wagonhas the same problem. I ended up wiring around the relay, just a short jumper around the relay and a short jumper near the pump from the ground wire to the body. I soldered them both in place and put some heat shrink tubing on them. It runs fine now. The relay is supposed to turn off the pump after ten seconds if the engine isn't started. Mine quit turning the pump on at all. I went to the dealership, and they didn't find one in any of their warehouses anywhere. They told me to do the fix that I did. Try it, I think that it will work, it did for me.

[Mark Humble]

Check fuse #11, 15 amp. This one powers the fuel pump relay, purge control solonoid, egr solonoid, aux air valve, and waste gate control.

[rayfordmachen]

To cd45,

Thanks for the suggestion on bypassing the relay. I'd read about that but thought I'd see if I could find the actual problem. If I'd realized it was going to be this much trouble I'd have jumpered the relay from the start, now I've spent so much time on it I want to see what the problem is.

 

to Mark Humble,

Interesting about the fuse. I had pulled each and every fuse one at at time and did a visual on them and they were all fine, but going back to the #11 you mentioned it is fine, except it's a 20A. I wonder if it's possible the 15A was blowing and they put a 20A in to stop that nuisance. A real short would pop either one of them. Could just be a total coincidence. I've driven another 87 turbo that hasn't blown a fuse in 8 years so it makes me wonder why that wound up with a 20A in it.

 

Thanks again for the posts. I'm still looking at it. I guess the ECU itself could be bad. I may swap a known good one into it. Would the known good ECU from an 87 Automatic Turbo 4WD work in the 87 problem car that is automatic turbo but only Front Wheel Drive?

[Cougar]

Are you getting spark to the plugs? If the ECU doesn't see the proper signal pulses from the CAS in the distributor then it will turn off the pump.

 

Also be sure fuse #5 is good. If the horn works it is ok.

[rayfordmachen]

Thanks Cougar and all. Yep the horn works, I was out in driveway at 3 in the morning and bumped it with my elbow

 

I took the ECU covers off and did a visual once over. Nothing obvious. Pulled a known good ECU and put it in , turned the switch to on and heard the sweet sweet 2 second rumble of a fuel pump, then started it and it ran great. Haven't been out on the street yet. I'll save that for tomorrow when I'm not so sleep deprived. Thanks all again.

 

Anybody have an ECU that will work in an 87 MPFI TURBO 4WD? I was at PAP Lakewood WA today and there was nothing there.

 

I sure hope the air suspension doesn't go through that box and I have to have a special ECU? I could get rid of the air struts if that's the case.

[Cougar]

I repaired mine that had this problem. It had a bad transistor. If you would like me to try and fix yours let me know.

[rayfordmachen]

That would be nice Cougar. I am an electronics nut myself. I tried to take a look and couldn't figure out the wiring and which actual connector and trace was from the fuel pump relay. I just did in circuit tests on as many transistors as I could see, but not the surface mount ones. Whew, noticed a few of those. Often in circuit tests of semiconductors is inconclusive because of parallel resistances etc. Could you point me to the which transistor it is?

 

If I can't fix it I'll drive it over to you to take a look at. Which road do I take?

[2alaskasubee]

so, what's the deal with the #5 fuse?

 

my 90 loyale (5sp4wdspfi) would not engage the fuel pump; the fuse was blown.

 

i was putting in an aftermarket stereo, and i guess i shorted sumtin

 

weird

 

sure was an easy fix

 

thanks

ross

[Cougar]

Fuse #5 powers a number of different things so you have to make sure it is ok. Since the horn is also tied to that fuse it is easy to check it by seeing if the horn works, telling you the the fuse is ok. I helped one person troubleshoot his ignition system and after a lot of testing to see what was wrong we found that fuse was blown. Always check the fuses first when you are having trouble.