High Fuel Pressure AirDog150

[jlwelding]

So ever since I installed this new pump and switched all my pricol gauges over to the new to me 02 3500 cab and chassis the pump pressure has been 21psi. I switched the 17psi spring back out for the 15psi spring and dropped it 1psi. With my foot in it it will only drop to 19psi. I have a new gauge coming to test my gauge but was just curious if this has been heard of before? I talked to AirDog and they werent very much help due to simply it is what it is until the new gauge says its the pump. He did mention cutting coils off the spring but I think the pump should go back if it comes to that. Thanks

[Mopar1973Man]

Buy a new spring like 6 bucks maybe? Or ask for a new spring from AirDog.

[wil440]

Not familiar with any electric LP as I have a mechanical pump.

Has this pump got a dedicated return back to tank, my mechanical pump has, it uses the original fuel supply line and my return from the cylinder head is what was the original return line so I have 2 returns, only asking as when I was testing my mechanical pump, if I restricted the pump return from the regulator fuel pressure went way high and if I had carried on it would have got that high it would have bust my 30psi gauge bearing in mind with a mechanical LP the more rpm the more fuel.

Correct me if I'm wrong but it was all fine until it was fitted to this new to you truck ??   Is it possible that "if" the pump has a dedicated return that it might be restricted somehow as in a soft line kinked or maybe a steel line kinked or if it uses the basket something is restricting the return there or it uses the small return at the rear of the cylinder head and it's just not big enough ??

If it has got a dedicated return line disconnect it and run it into a bucket then see what psi you have

It could well be that the gauge is reading wrong but other than restricted return lines or smaller return lines from one truck to another I can't see how a relief spring actually grows from one truck to another to increase FP from one to the other, this is assuming I've understood that your fuel pressure has increased ??

 

And I can see around 22psi ish at anything over 2300rpm, doesn't bother me as I never go over 2300 anyway

 

Edited February 15, 2022 by wil440

[jlwelding]

I have the return from the head still hooked up to the factory in the tank basket. I cant confirm there is not a restriction there but when I ran it by AirDog he didnt seem to think it was a issue. Return from the pump is connected to the filler neck and dumping into the tank. Still waiting on gauge to confirm pressure.

[Mopar1973Man]

Only thing you don't want to do is draw fuel from then sender basket. Typically much hotter fuel.

[jlwelding]

1 minute ago, Mopar1973Man said:

Only thing you don't want to do is draw fuel from then sender basket. Typically much hotter fuel.

I have a draw straw installed. Basket is just for fuel sender and return. 

[wil440]

34 minutes ago, jlwelding said:

I have the return from the head still hooked up to the factory in the tank basket. I cant confirm there is not a restriction there but when I ran it by AirDog he didnt seem to think it was a issue. Return from the pump is connected to the filler neck and dumping into the tank. Still waiting on gauge to confirm pressure.

It's the return from the pump that really increases my FP when restricted slowly with a brake pipe clamp, didn't check what the head return did when restricted as mine all factory and not easily compressible to restrict

 

17 minutes ago, Mopar1973Man said:

Only thing you don't want to do is draw fuel from then sender basket. Typically much hotter fuel.

Mine draws from the basket and both returns go back to that, I have made a filler neck return but not got around to fitting it, my fuels temps are around 80f this time of year after say 40+ miles towing and might get to 100f in the summer, but as I've said before my LP moves a LOT of fuel and after testing return flow last summer I know my truck does not puddle hot fuel around the basket