Car Won't Start ...fuel pump?

[eR1c]

I have a '77 930 (it's actually a late model w/ the '78 3.0 engine).

Car won't start, I've verrified that it has spark and the battery is new. My guess is the fuel pump? I've tried letting it crank, pumping the gas slightly as I start it, etc... can't get it started.

Should I have it towed to a mechanic? or does anyone know if this is a common issue and could be the fuel pump? How difficult is it to replace the fuel pump in the 930? ..I'd hate to spend $250 for a fuel pump only to find out that isn't the issue ...hence why I wonder if I should have it towed somehwere?

comments and thoughts very welcome...

[CliffBrown]

In a CIS system moving the gas pedal (throttle) will not supply more gas until the motor has started, just more air.

Pull an injector or disconnect an injector line at an injector, then check to see if you have fuel flow while someone tries to start. A fire extinguisher nearby is preferred during this test.

[ninesixfour]

Did you try replacing the fuel pump relay?

[eR1c]

just tried that, no fuel visible.

I did spray a little gas near the intake and it started for a few seconds then died.

[eR1c]

i have not replaced the fuel pump relay.
where is it located? -in the fuse panel box? if so, is it marked?

thanks,

[ossiblue]

Originally Posted by eR1c

i have not replaced the fuel pump relay.
where is it located? -in the fuse panel box? if so, is it marked?

thanks,

Not sure if 77 has a relay (earlier cars up to at least 75 didn't) but if it does, it would be in the engine compartment, driver's side behind the plastic shield and it will be red, I believe.

If you can jump the relay contacts, the pump should start if it is good.

[boyt911sc]

Originally Posted by eR1c

i have not replaced the fuel pump relay.
where is it located? -in the fuse panel box? if so, is it marked?

thanks,

eR1c,

Since you are not familiar with your car's electrical configuration, it would be easier for you to follow some of the suggestions by posting a picture of your fuse panel (front). And from there we will direct you how to do the fuel pump test.

After you have located and identified the FP relay (red), connect terminals 87a & 30 using a suitable jumper wire with fuse (mandatory) and a switch (optional). This instruction is available in Bentley's SC manual page 240-11 in case you know someone who owns one. This test is widely covered and discussed in this forum so searching might help you get a better understanding of the things to do.

There are a lot of guys in this forum that will help you get started. Keep us posted and we will be by your side until you solve your problem/s. Good luck.

Tony

[eR1c]

I can't tell you how much I appreciate your help.

I will post a photo soon,
(need to help get the kids to bed first)!

[carson911s]

It's a round red one.

This happened to me the other day. I removed and replaced it a couple of times and all has been well since.

[eR1c]

here's a photo,
according to the inside of the fuse box cover it's the first fuse ..the large red one in the top left of this photo.

[eR1c]

Carson, that is very encouraging ..i hope it's as simple as a $15 fuse in my case as well.



how did you test it? -should I do a search ..or can you guys walk me through it?

[eR1c]

(by the way I am very mechanically inclined, have help rebuild many parts and have done lot's of mod's on my other cars (Mini Cooper + Jeep) ..yet when it comes to electrical ...well it's not my thing.

[Gogar]

If you're absolutely stranded, I think you can swap the two red ones and you'll know. Unless that second red one is something crucial as well . . . . . .

[Mr9146]

Pull the plug off the sensor plate ... that'll let the pumps run when the key is put in the ON position (as opposed to only when cranking). At that point, you'll be able to actually hear the pumps running and can pull the relays one at a time to see if all is well and good.

This should help diagnose the problem but, be aware, you can easily flood the motor by leaving the key in the ON position ... plug the sensor plate back in when you're finished.

[spuggy]

Originally Posted by eR1c

here's a photo,
according to the inside of the fuse box cover it's the first fuse ..the large red one in the top left of this photo.

The front fuel pump is controlled by the red relay on the left.

I think you'll find that the rear fuel pump is the next red relay.

You'll definitely need both pumps functional for the car to run well, although I think it should start and run (think "limp-home") with only one.

[eR1c]

thanks, going to try it today around 2 (when the kids are napping). I have 2 small boys (1 + 3yrs). -seriously limits my car time!

[ninesixfour]

Originally Posted by eR1c

I have 2 small boys (1 + 3yrs). -seriously limits my car time!

I hear ya. Two boys, 2 and 9 months here.

[eR1c]

ninesixfour, ..yep you know what I am talking about!

Looks like it is the relay. Yeah! -that's an easy fix!
I am ordering 2 of the fuses ...so I can keep one as a spare in the glove box. I hate the idea of being stranded somewhere because of a stupid relay switch.

[Joe Bob]

Spray quick start in the intake when you're cranking the starter....if you get a cough, it's fuel issue.

With CIS FI, it doesn't help when it comes to pumping the pedal. That's carbs.....

[spuggy]

Originally Posted by eR1c

Looks like it is the relay. Yeah! -that's an easy fix!

Uhhh, I don't think the relays go bad very often on CIS cars... Try swapping it with one of the black relays if you want to check.

And before anyone tells you the red relays have magic internal extra bits (actually, they do), I've been running a black one for my fuel pump for at least the last 3 years/25,000 miles (and probably some considerable time before I bought the car as well) and it's still working fine.

Originally Posted by eR1c

I am ordering 2 of the fuses ...so I can keep one as a spare in the glove box. I hate the idea of being stranded somewhere because of a stupid relay switch.

Now there's a thought. You knew the fuel pumps are fused, right?