83 308 QV Fuel Pump Issue

Hi all,
Had my car in storage for the winter. Went to start and just cranked. Seemed like no fuel. Heard clicking from the relays. Fuse #3 has continuity and 12 volts. It's been a while, so for $8 I replaced the fuel pump relay and the start injector relays. Still no start. Pulled the air flow safety switch connector, put key in position II and I do not hear the fuel pump running. It should run with the safety switch disconnected, correct?

Is the easiest thing to do is to get to the power lead on the fuel pump and verify 12 volts are present with the above condition and if so, assume the fuel pump is dead?

Thanks for the help!
GT

 

Yes (but the start valve relay has to also be working correctly).

Did you measure this with the safety switch unplugged and the key "on" (i.e., under load)? If the fuse block rivets/plates are flaky this can measure +12V when not under load, but drop to a lower voltage when under load.

One other easy thing you can do is remove the fuel pump relay and just use a jumper wire to connect the 30 female terminal in the relay socket to the 87 terminal in the relay socket:
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The fuel pump should run. If not, measure the voltage (with the jumper in place) between the 87 terminal and ground. If it is +12V (with the jumper in place) but the fuel pump doesn't run = bad sign for the fuel pump itself (or the local wiring at the fuel pump -- so you would need to go there next to confirm/deny +12V at the fuel pump itself). If it isn't +12V = you have some other upstream wiring problem.

PS They mangled the relay labeling in your OM. Both relay G and relay P are called "relay for start injector" in the relay section, but I believe relay P is the one controlling the fuel pump relay -- called "90 - start valve relay" on the schematic (you can compare the wire insulation colors to those shown on the schematic to be sure). Relay G is what operates the cold start injector.

 

I mangled my PS (and ran out of edit time) -- although relay P is listed in the relay table it is not shown in the figure -- relay G is it.

 

Thank you Magnusson, I noticed that in my OM. There is no P. So the jump wire from female pin 30 to 87 above is on the fuel pump relay location "H", not the start injector location "G", correct. Also, I assume the jumpers should be installed and voltage measured with the safety connector plugged back in at the air box, correct?

PS - my eyes suck.. I can't read the wiring diagram, need to go buy a magnifying glass tonight.

 

Also, I replaced both the fuel pump and start injector relays with new Bosch relays to be safe.

 

I should have stated also that I replaced my fuse boxes several years ago with Birdman's fuse boxes and new fuses. So I'm pretty confident the rivets and plates are okay.

 

Correct.

No, it doesn't matter whether the safety switch is plugged back in, or not, when using the jumper (nor does it matter whether the key is "on" or "off").

 

Finally, I didn't mean to call you by your last name! I only grabbed half with my cut and paste! Sorry Steve!

 

Makes sense as by performing the direct connection, I'm basically bypassing the control from the start injector and manually acting like the fuel relay making the connection between the two pins. Got it. I'm going to try that. I need to make a proper jumper cable. I will also measure the voltage drop (if any) at the fuse for the fuel pump when it should be under load.

 

And then if no pump spinning, push the car out of the garage and into the other stall where my lift is to get at the fuel pump wiring to test for 12v.

 

Yes, your schematic only shows one wire connected to terminal 87, and, since the relay has two 87 terminals, I should've said use whichever 87 terminal position has a female metal contact in it.

That "thump" does sound like something you'd get with a stalled/binding fuel pump, but there are some other things powered by this relay (like the AAV heater) so those would give a spark, too. But the bottom line is that since you failed this test, it does justify getting under the car to the fuel pump itself and make a voltage measurement there when the jumper is in place. If you get +12V there between the two terminals on the fuel pump motor, and it doesn't run = you can buy a new fuel pump without regret. Good Hunting!

 

Thanks Steve... I just had my son connect the jumper wire and I had my stethoscope directly on the fuel pump. The noise is definitely coming from the pump. Now I need to get it out of there and make sure I order the correct one. I think it's the one with the internal valve - Bosch 0580254975 (Bosch 69523). I'll get a better look at it when I get under it tomorrow.

Thanks again for your help!
GT

 

It sounds like you're narrowing it down to the fuel pump, but with regards to the above - I put in Birdman fuse boxes in my 308 QV 7 years ago; and 2 years ago found that the rivets and soldering on one or two connections had loosened. It's always worth checking and confirming!

 

I have a 308 QV US built in November 1984. I recently had the fuel distributor rebuilt and replaced the pump, accumulator and filter. Larry Fletcher, who rebuilt the distributor, suggests that you connect the input and return fuel lines and run the pump "for at least an hour" in an attempt to thoroughly clean the system. I relied on this very useful thread to do so. After some confusion regarding incorrect OM information and relays G,H and P, I initially discovered that jumping relay H ran the frequency valve and not the fuel pump. I then switched my jumper to the other 87 connector on that H relay. That ran the fuel pump and NOT the frequency valve. I don't know if all cars are set up like mine, but I thought this information might be helpful to other owners.