I have no fuel pressure?!?!

clthorn

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So I have a 1992 7.3 idi N/A and I removed the fuel filter vacuum sensor and installed an oil filled 0-15psi guage. I have a racor electric fuel pump and with key on engine of I have 6 psi of fuel pressure. With engine idling I have 0 psi.

Is the port for the vacuum guage a good spot to to measure post fuel filter pressures? I want to be able to see what pressure my injection pump is truly getting
 

DrCharles

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That spot will work, but the question is why does it drop to zero with the engine running... either there's an obstruction in the fuel system, or the pump is no good.

How does the truck run and drive? Does it hesitate or bog when you're trying to accelerate at full throttle? Does the fuel filter light come on (showing vacuum at that port) with the switch reinstalled?
 

clthorn

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Truck runs and gets me from a to b but I have never checked fuel pressure since installing this pump 2 years ago. It doesn't seem like it has ever had a starvation issue but it definitely isn't a powerhouse. The switch I removed never worked because the connector is missing. I ordered a universal 5-7 psi inline pump and check it again.

I was scared there might have been a check valve or something internal in that port
 

Thewespaul

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How do you have the pump wired? Are you using a relay? You may just not have enough amperage to the pump or a clogged filter
 

clthorn

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It's on a relay, I use the fuel shut off solenoid as the trigger wire
 

The_Josh_Bear

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Check the main filter or any other filters installed aftermarket. I had a big problem with a small inline pump years ago, it had a little pre-filter on it that clogged up after quite a while. So long I forgot about it and it took me 2 days to figure out the problem!
If that all checks out:

The GPH is important with these setups. I don't know what yours is rated for but it's possible the IP's internal transfer pump is out-pulling the e-pump in volume. Obviously it's running fine so it's not a huge issue, but it'll probably perform better and have more accurate timing with proper fuel flow.
I have the Facet Duralift 40223 9-11.5psi and 33GPH. Honestly I think that 33GPH is marginal at best given how much my pressure drops at zero-load revving in the driveway. I cant see the gauge when under way and I'd bet it's even lower then.
 
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