Fuel pump not running..

[Timebender]

Hi guys,
I seem to be having an issue with getting fuel to my engine - at first I thought it was the second inline pump that was installed that was giving me problems, so I took it out and put in a fuel regulator. However, when I turn on the car, with a new RMP relay, I can't hear the in-tank pump coming on - and I tried the jumper from 30 to 87, and still no sound.

I checked the #7 fuse with no luck, and replaced the smaller lambda relay a while ago, so at this point I'm going to guess my fuel pump finally gave out.
Is there any way to check before putting in a new tank pump?


Thanks!

Greg

[Bitsyncmaster]

You need to get a voltmeter right on the two fuel pump terminals. With the RPM relay connector jumpered (brown wire to white/purple) you should be getting at least 11 volts on the pump terminals as long as your battery is good.

The fact it ran when your turned the key and not jumpering makes me think your battery may be dead.

[Nicholas R]

Is this portion of your engine swap still stock? Just curious; I know I have no use for the RPM relay. I suppose if you have a manual distributor, you can still use it. Still if you had 2 fuel pumps wired up, there must have been at least some wiring modifications.

[Timebender]

I'll have to check to see if the pump is getting power. The battery is charged and showing 13 volts, the engine cranks when it wants (that's a whole other story with the starter...).

As far as the setup, yes it's kinda stock. What they did was kept the original pump in the tank, then added a second pump inline, most likely to either increase or decrease the internal pump PSI, as the engine only needs 5 psi.

The second pump would get ignition signal from the RPM relay, with a wire going from the ignition signal on the main (accessory relay 2) to the RPM relay pin 87b. So when I'd turn the key to ignition, you could hear the second pump come on.

And that worked great for a long time until recently.

Because there was no more sound at the second pump. And so I replaced the RPM relay, with still nothing. But if I jumpered from 30 to 87, even with no key on at all, it would run. And the engine would run. But if I tried that with the RPM relay plugged in, it would run as long as I was giving it gas. As soon as my foot was off the gas, the engine would die as it wasn't getting enough fuel.

So now the second pump is out of the equation- just to make things simpler. But the main pump I don't hear running either, with the relay jumpered, and the engine is getting no gas. I checked the fuse, it's good. Maybe my inertia switch was bumped or just bad which is possible.

I'm curious as to how to keep the internal pump going without needing the RPM relay.

My next thing would be too remove the internal pump or gut it, so it still is in the tank, then put a mechanical pump back on the engine.

[Bitsyncmaster]

It may be you have a bad pump. So you either buy a voltmeter or pump to find out. My car had a bad connection on the fuse and a bad connection at the two pin connector up near the pump. It still ran so I would have never found those bad connections without using my voltmeter.

[Timebender]

I'll get the voltmeter on it when I get home.

Interesting though you mentioned the fuse connection - when I swapped out the fuse, briefly the rpm relay kicked in and you could hear the secondary pump come on, and the relay would click on and off back and forth like it was getting a intermittent connection. So it might be just a dirty fuse terminal, but I'll look under the fuse box as well.

[skill]

Hey Timebender, If you upgrade to the electronic. Let me know and I can help you out! I upgraded 3037's a year ago from that archaic ass-metal fuel pump from Jakku and have not had any issues. Will help you out but you'd have to tow it to Chula Vista! :) Or I can get a break and head on out to Jamul! Let me know! Bri

[Timebender]

Let's talk. Did that allow you to get rid of the RPM relay too?

[David T]

Let's talk. Did that allow you to get rid of the RPM relay too?

Timebender, you said you had a conversion motor. How are they running it? If you have an engine management system you should be able to have it run your fuel pump and not use the circuit from the Delorean fuel system. Then you would have no need for the RPM relay. I would still try to keep the inertia switch on the ground side as a safety in case of an accident.

[Timebender]

The conversion was to a 350 sbc when the original owner bought the car back in 81 over in the Illinois area. Turns out the secondary pump might be the only pump - as you can see, that's not a pump at the tank as far as I can tell but a siphon, as there aren't any electrical wires connected to it, or wire lugs on it. So the inline pump would run fine with the rpm relay connected and the key turned to ignition. It also would run when 87 and 30 were jumpered. Also, if I took out fuse 7, the pump would still run.
Interestingly enough when I thought I was having Rpm relay issues and put in a new one (one of Dave's) it ran well with no issues.
And then one day the inline pump stopped working- or it would briefly run then stop, but if I jumpered it, it ran fine.
There is a wire that connects the ignition (white) wire coming out of the second accessory relay to pin 87b on the rpm relay, which I'm assuming had something to do with that pump. If I put in a new relay, then I'd get no power to it.
At this point I might as well hook up the mechanical pump and call it a day.
39784

[Timebender]

Oh, and I don't think the inertia switch was ever hooked up...

[Timebender]

Being my car has a nice Chevy 350 small block, I decided I'd go the easy route and just put a mechanical pump back on, take out the inline pump, and call it a day. So I bought all the stuff I needed (pump, pushrod, hard line, hose clamps, pipe bender, etc.) and went to remove the mechanical pump cover on the engine. To my dismay, there was no hole for the pushrod. There's a little circle there where the hole would go, but it's part of the casting.
Turns out late 80's and on 350's didn't have that anymore due to Chevy moving to a throttle body injection - and the mechanical pump wouldn't put out enough fuel pressure.

So back to putting in an inline pump. I ordered a new Carter pump that's like the one that was in there (though an updated version), and am replacing any relays that would have been causing the sudden issue with the old fuel pump not running except when the rpm relay connector was jumped.

Fingers crossed.

And I might just find a way to hook up the pump to the ignition without the need for the RPM relay sending voltage.

If anyone has an idea where I can get that from up front, I'm ready for any suggestions.

[SS Spoiler]

Is there also possible no eccentric on the cam to drive the
pushrod / pump?

[DMCMW Dave]

Being my car has a nice Chevy 350 small block, I decided I'd go the easy route and just put a mechanical pump back on, take out the inline pump, and call it a day. So I bought all the stuff I needed (pump, pushrod, hard line, hose clamps, pipe bender, etc.) and went to remove the mechanical pump cover on the engine. To my dismay, there was no hole for the pushrod. There's a little circle there where the hole would go, but it's part of the casting.
Turns out late 80's and on 350's didn't have that anymore due to Chevy moving to a throttle body injection - and the mechanical pump wouldn't put out enough fuel pressure.

So back to putting in an inline pump. I ordered a new Carter pump that's like the one that was in there (though an updated version), and am replacing any relays that would have been causing the sudden issue with the old fuel pump not running except when the rpm relay connector was jumped.

Fingers crossed.

And I might just find a way to hook up the pump to the ignition without the need for the RPM relay sending voltage.

If anyone has an idea where I can get that from up front, I'm ready for any suggestions.

Rewire it to use a standard relay activated by the main (run) relay. Don't run the pump directly off the ignition switch. There really isn't any reason not to continue using the rpm relay IMO for safety reasons.


Sent from phone

[Timebender]

So you're saying find a place to put a relay (in the relay compartment?), which is activated by the silver accessory 2 (which I'm guessing you mean that one), and then have the pump come off that? Here's what I've been discovering along the way as I've been working on the car.
1. The original fuel pump, and its wiring, were taken out when the conversion was done. Thus when DMC Ca went to update the in tank pump by taking out the siphon, they couldn't get it to work - as there isn't any wiring for power. Well, what Danny said was they couldn't get the engine to run with the pump/sender combo, so they put my original pump back in the tank, and left the IN LINE pump attached as well. They figured it wouldn't run with the new combo pump and inline pump.

I paid for them to do the swap, then swap it back to the original pump that was in there, which it never was- it's always been a simple siphon that runs to the inline pump.

2. The inline pump has a power line running to it and a ground to the frame right near it at the front left corner of the car. It comes on - or used to, with the ignition key on. If you remove the fuse that's for the normal, in tank pump, which there isn't a pump, the inline pump still runs.

3. The original owner ran a separate wire from the ignition line on accessory relay2 and tapped into the line for tab 87b on the rpm relay. If you removed that wire from the original line, no pump.

4. All had been working fine, though I wonder if removing the lambda module and the other one from behind the drivers seat screwed things up, because even though the car would still start and run, it would cut off once in a while like the pump would just lose power.

5. If I did the hot start trick by jumping 30 to 87, the pump would run, with no key in the ignition.

So for now, I have that wire coming off the ignition tab on the main huge accessory relay #2, and going into the slot for 87 directly, and the pump now comes on when I turn the ignition on.

All the time I've had the car, it never relied on the engine running (thus creating rpm's) for the RPM relay to really do it's job. The tach signal from the distributor coil goes directly to the tach.

What I can do though, is I ordered a new oil pressure switch that has a cutoff. But I have to get the car in the air to run a wire from that up to front and to the pump. Or run it through the car I guess.