Help! Keeps poping fuses

[Marv02]

It sorta runs.
1986 Coupe
After putting the New 383 in.
It's poping fuel pump fuses.
I can jump ADLC to the G port straight to the battery with a new fuse works fine runs Fuel pump.
Remove the Jumper wire using just the Key I have power to the fuel pump but after starting the motor it a it blow the fuse I checked the wireing cant find any thing wrong with it use a meter good conections good voltage.
Replaced the Relay it has a new Oil pressuer switch.
I have upped the fuel pressure up to 58.5 with a walbor fuel pump if this has any thing to do with it blowing fuses I dont Know.
The pump worked fine before the motot swap.
I out of Ideas.
HELP

 

[John Robinson]

Check the amps draw on the new pump. It sounds like you put in a fuel pump that draws more amperage then the stock pump in which case you will have to up the fuse amp load to carry the new pump. Also I think you have two fuel pump fuses in the fuse panel. Be careful if you increase the fuse amps that you don't over heat the wiring to the pump etc by putting more amps threw it than it was designed to carry. That is why there are different sizes of wire in the wiring harness they are sized for the amp load.

 

[boomdriver]

It sorta runs.
1986 Coupe
After putting the New 383 in.
It's poping fuel pump fuses.
I can jump ADLC to the G port straight to the battery with a new fuse works fine runs Fuel pump.
Remove the Jumper wire using just the Key I have power to the fuel pump but after starting the motor it a it blow the fuse I checked the wireing cant find any thing wrong with it use a meter good conections good voltage.
Replaced the Relay it has a new Oil pressuer switch.
I have upped the fuel pressure up to 58.5 with a walbor fuel pump if this has any thing to do with it blowing fuses I dont Know.
The pump worked fine before the motot swap.
I out of Ideas.
HELP

Your low oil pressure switch is probably shorted or grounded. Thats an alt path for power to get to the pump. If the normal route thru the relay can;t work that 2nd path will. Its a back-up power source but it IS a hot wire thats just looped across an on/off switch. Thats rare on a C4. Usually everything is grounds, but this back-up fuel circuit is hot wires. take the fuel pump relay out and see what happens...should start but if that is the short, the pump will die as that fuse blows. Pull the low press wires off the switch, reconnect the relay and see if it will keep running. That test one circuit or the other.

 

[Marv02]

This what I came up with.
I was told by Jon form FIC to turn the Fuel pressure up to 58.5to work with the 383 motor.
Now it pumping harder it needs more Amps to do so thats why it blowing fuses.

 

[Marv02]

It works with a 20 amp fuses I goning to try a 15 and see if it holds.

Check the amps draw on the new pump. It sounds like you put in a fuel pump that draws more amperage then the stock pump in which case you will have to up the fuse amp load to carry the new pump. Also I think you have two fuel pump fuses in the fuse panel. Be careful if you increase the fuse amps that you don't over heat the wiring to the pump etc by putting more amps threw it than it was designed to carry. That is why there are different sizes of wire in the wiring harness they are sized for the amp load.

 

[boomdriver]

This what I came up with.
I was told by Jon form FIC to turn the Fuel pressure up to 58.5to work with the 383 motor.
Now it pumping harder it needs more Amps to do so thats why it blowing fuses.

58 psi at the regulator?

the regulator won;t handle that. You'll end up having to get the right injectors...58 is too high....the downside is things coming apart and leaking internally and externally. These rails are not designed for that kind of pressure.

I'd plan on getting some 32 lb/hr injectors ( you're using 28 lb/hr now?)so the pressure can be a reasonable number....like 35-40psi. remember the rest of the fuel system don;t get a choice and its not gonna hold close to 60 psi. Thats a 50% increase over the system design. I see O-rings leaking everywhere. I see a diaphram blown in the fuel regulator. They make a high pressure regulator just for big motors. The stock or semi stock adjustable just ain;t tough enough to do 60 psi for very long. Add surges...drip drip drip...

And something is not sounding quite right. The pump runs and puts out the same pressure and same volume all the time. The pressure is either dumped to the return line or sent to the rails for the injectors. Setting the regulator to 60 does not cause the pump to run harder. It always runs that hard. The extra pressure was going somewhere else before.

JMO,
but I think setting small inj that high is asking for trouble.....

How come the old pump did'nt blow fuses with the same injectors? somethings wrong here. This new pump should be producing this flow easier...pressure is NOT Volume. The new pump is making extra volume. Most of thats going back in the return line.
I'd damn sure question a high resistance in a hot wire running thru the gas tank....and sticking a bigger fuse in? Nooooooo. All thats gonna do is force something else to melt.
Before you do that, contact the Walbro people and ask them if their pump has that much resistance and needs the bigger fuse. Ask if thats normal before experimenting with a hot wire in a bomb.

 

[John Robinson]

Check the amps draw on the new pump. It sounds like you put in a fuel pump that draws more amperage then the stock pump in which case you will have to up the fuse amp load to carry the new pump. Also I think you have two fuel pump fuses in the fuse panel. Be careful if you increase the fuse amps that you don't over heat the wiring to the pump etc by putting more amps threw it than it was designed to carry. That is why there are different sizes of wire in the wiring harness they are sized for the amp load.

Boomdriver brings up good points about volume verses pressure. Please note I said to check the amp draw to determine if a larger fuse is in order. Also as Boomdriver also points out that putting a larger amp fuse in can over load the wiring and cause it to overheat. Perhaps the thing to do at this point is to reinstall the original pump and see if the car will run that way with the 10 amp fuses. Then do the research to determine what amps the new pump is drawing. As for the seals withstanding that much pressure Boomdriver is right in cautioning about the fuel line seals not being designed to hold that much pressure. Believe me when I say back in late May I had a seal on the fuel rail fail and pumped 1/4 tank of gas all over the engine. With the pressure load you are putting on them you could do the same thing and have it all go up in a big ball of fire.

 

[Marv02]

Thanks I turn the pressure down tomarrow I am tired working on it for today.

 

[boomdriver]

Thanks I turn the pressure down tomarrow I am tired working on it for today.

I'm not trying to play "chicken little" or anything...but this situation scares me a little and I'd really hate to see something go bad after all you;ve gone thru with this car.
Take your time, take a step back if you have to. The dream ain;t going anywhere. It's well within reach at this point. Don;t get tripped up this far into it

I think following Johns suggestion of using the old pump until the spec of the new one is known, is the best plan at this point.

I know you just want to drive your car...

 

[Marv02]

I using the same fuel pump as before I was bored so I went out and turned down the fuel pressure to 45 LB's and put in the old 10 AMP Fuses didnt pop I going to leave it that way.

I have to call the guys who making my new chip and let them Know I went back to the 24# injector set up.

I'm not trying to play "chicken little" or anything...but this situation scares me a little and I'd really hate to see something go bad after all you;ve gone thru with this car.
Take your time, take a step back if you have to. The dream ain;t going anywhere. It's well within reach at this point. Don;t get tripped up this far into it

I think following Johns suggestion of using the old pump until the spec of the new one is known, is the best plan at this point.

I know you just want to drive your car...