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Juan Crespo
Juan Crespo, Tech Trainer
Category: Ford
Satisfied Customers: 1523
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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1988 ford ranger 2.9 (my neighbors) He has replaced both

Customer Question

1988 ford ranger 2.9 (my neighbors) He has replaced both relays, and the frame rail fuel pump. I went to look at it and tested high and low circuits both have power, then I put a jumper wire on terminals #3 and #4 and I can hear rear fuel pump kick in, there is also power at the frame rail pump, I ran a hot wire with test light to ground on the wires to frame rail and ground is good. why no power when relay is installed what am I overlooking.
Submitted: 1 year ago.
Category: Ford
Expert:  Juan Crespo replied 1 year ago.

What are we trying to diagnose? Cranks but won't start? or no fuel pressure at the rail?

Customer: replied 1 year ago.
cranks no start, and no power to fuel pump with out jumping terminals
Expert:  Juan Crespo replied 1 year ago.

Sorry, but I'm confused; are you saying the engine won't start even if you jump the fuel pump? Are you checking fuel pressure with a tester connected to the rail? Have you made sure there is compression, spark and injector pulse and the only cause of the no-start is lack of fuel pressure?

Customer: replied 1 year ago.
I will be back in 15 minutes
Customer: replied 1 year ago.
I am back
Customer: replied 1 year ago.
OK, I am troubleshooting a 1988 ford ranger with 2.9 cranks but wont start but will start if you spray starting fluid in it and run until either is burned out.
It has had relays and the frame rail fuel pump replaced, then I was asked to see if I could get it going, I removed the relay and checked for power on terminals #2 & 4 both had power with key on. Then I jumped terminal #3 & #4 and could hear the rear fuel pump come on- at that I figured the inertia switch was ok. I also checked for power at the frame rail fuel pump and found power to it with key on, I also ran power to check the ground at this fuel pump and it was good. when I remove jumper and install relay I have no power to pumps what am I overlooking.
Customer: replied 1 year ago.
when I remove jumper and install relay I have no power to pumps what am I overlooking.
Expert:  Juan Crespo replied 1 year ago.

Well, as it is, by the starting fluid test we know compression and spark are good. What we still don't know is whether or not the pumps can deliver the 35-45 psi fuel pressure the injectors require, or whether or not those injectors are being pulsed open by the computer.

So here is what I would do; I'd go to the parts store and buy a Noid light (less than $15) to check for injector pulse and I would also borrow a fuel pressure tester to check what kind of pressure is going to be available at the rail once I jumper both fuel pumps - or just borrow the fuel pressure tester and gamble on the injector pulse.

Or, you can gamble on both the fuel pumps being good and the injectors being pulsed and just repair the fuel pump circuit.

It's up to you, I'm on your side and will help you with whatever you choose to do.

Customer: replied 1 year ago.
Hi, please credit back my money less the deposit. Nothing personal but you didn't really address my question you just sort of gave a vague response. (the problem was a bad ground at the rail pump) Thanks - Steve
Expert:  Juan Crespo replied 1 year ago.

Nothing personal indeed. Please refer to customer support for any money matters.