A few months back you guys helped me solve a Fuel System problem on my 87 B2 (https://www.ford-trucks.com/forums/6...l-problem.html). It was a disconnected ground to the ECM. The symptoms were that the fuel pump would not run, and even when I applied direct power to it and built 40lbs of fuel pressure it would not start. Connecting the ground solved the problem (thank you turret_plug). I drove it a few times and parked it to work on my 71 F250 (I have way to many projects). When I finally got back to the B2 the pump would not work again. So first thing I did was start checking grounds, they all seem to have good connection and using a Power Probe I have been able to probe all the grounds with a direct ground as well. This time when I supply power to the pump it starts and runs fine. <O</O

With key on, @ the Relay: I have power to Yellow (key on or off), Red, Tan/Lt Grn.
I do not have power @ Org/Lt Blu. Org/Lt Blu is direct ground. If I connect power to Org/Lt Blu the pump runs constantly and the engine will run.<O</O

I have swapped relay with a 88 B2 (not known to work), and I have swapped ECM with a 88 B2 (not known to work). I have continuity through the Inertia Switch.


The original ECM gets a code of 31 (EGR). When I first hooked up ECM from the 88 B2 I got a code of 95 (air flow or possible fuel circuit problem). When I had the 2<SUP>nd</SUP> ECM installed and probing wires I put power to a ground and now the 2<SUP>nd</SUP> ECM does not show any codes.<O</O

Could I have 2 bad Fuel Pump Relays? Could I have 2 bad ECM’s (obviously I now have at least 1 bad one)? Where else should I be looking?
<O</O

Thanks

Chad

 

The voltages look good.

See this link & with the key on, ground the fuel pump pin at the EEC-4 test connector.

http://fordfuelinjection.com?p=13

Do the pumps run?

That pin is spliced to the tan/light green between the ECM & the pump relay.

 

Happy Easter 87; The fuel pump wire at the EEC-4 Test Connector is direct ground with key off, with key on it has +13 Volts (with the 2<SUP>nd</SUP> ECM installed, key off = direct ground, key on = open circuit). When I take it to ground the pumps still do not run
<O</O

Thanks for the link, all the info I can get helps me understand this sytem a little more. I wish I could get my head wrapped around these EFI Systems. They are a bit different from the points on my FE.

 

And a happy easter to you.

You should see key on voltage at that pin & when you -or the ECM- grounds it the pump relay should close & the pumps should run.

Key off should be an open.

 

OK so when I ground the fuel pump wire at the EEC-4 Test Connector, the pumps still do not run. So even if the ECM is not taking that circuit to ground we have discovered that the relay is bad?
I tried my local auto parts for a replacement relay, they claim not to have one.

 

Yeah, if you have 13 volts on that pin & grounding it does'nt close the relay then it does looks like the relay is shot.

 

Thanks for the help 87; I will track down a relay and try that. I’ll post when I have more info your help has been great

 

I picked up a relay from a wrecking yard and installed it; works great. Thanks for all your help. I couldn’t find one of these at any of the auto parts stores locally or on line. Where would I get a new one if needed?

 

Good deal, glad that worked for you.

Strange that you cant find a new relay though???

It's been awhile, but the last relay I bought was from Napa & Autozone should also have it.

 

I am asking for a fuel pump relay; they (Napa, Advanced Auto, and Autozone) say that they don’t show that part in there system. Should I be calling it something else?

 

Well go figure. I called my local Napa & they want -OUCH- 14 bucks for the "fuel pump relay". Autozone wants -ouch- 12 bucks.

At those prices, you might want to pickup a couple of extras the next time you're at the bone yard.

It's simple enough to bench test them & make sure they do work.

 

The 87/88 ECM are not compatible with each other and will throw codes, the reason you might be getting a code is because there is no EGR on a 1988 for one thing.