Pop out the fuel pump relay and switch it with another to test it. It's free and only takes 5 minutes.

 

I've done that; and even switched it with a new relay I had just hoping it would be the problem.

It's acting like the fuel pumps are having trouble priming up. I did notice when it was starting up fine the fuel pressure would jump way up into the mid 40's as it was starting. Is that normal?

 

Casey, could it be that you got a bad set of pumps?

Why don't you switch back to your factory pumps and see what happens.


Suavy

 

Casey -

Could we put my ecu in you truck and just flash a copy of your tune on it to get around the pats?

I can reflash it with my tune afterwards. I would eliminate the ECU I would think.

Bob

 

Maybe the resistor under the front of the truck has fried (or otherwise gone bad?) Or maybe the connections to it are shady....

You can try bypassing the resistor and run the pumps at the full 12v (instead of the stepped voltage) by installing a jumper like this:



Also, never checked the voltage at teh connector for the pumps, but it sure does seem like one pin should be a dedicated ground.. I cant believe ford would rely on just the assembly having contact
through the lines or something as a ground...

Maybe you've got some kind of screwy wiring problem (which would suck, bad.)

-Dale

 

Well; I got it running consistently tonight, but am not totally sure what's up with it. I drove it, got it to start/stop about 30 times without a problem. I was trying to figure things out, and was in the fuse/relay box under the hood. I was pulling/replacing the main powertrain relay I beleive it was called, and listening to the pumps come on and off. Then they stopped. So, I kept pulling/replacing it and was trying to figure out what relays were clicking and clicking again. When I put my finger on the wiper motor relay. It started working again. I ended up pulley that relay(I no longer have the wiper motor in the truck). Since that I have not had one problem out of the fuel pumps

Now my only problem is when driving the truck is having trouble going from low to high pressure as driving and rolling into the gas. It will actually let the pressure drop when I start to roll into the gas, and then levels off, but is not going up. Then with a little more gas it finally clicks on, and the pressure jumps. Before the high clicks on the truck trys to run really lean. But, WOT the truck is looking excellent a/f and fuel pressure wise.

Is that a regulator problem(30# at idle 36# with the vacuum line off) Or, do I have a problem with the high low relay/resistor.

 

Would there be any reason you couldn't run the jumper all the time? What is the purpose to stepping the voltage?

 

I run the jumper all the time..

Im not sure why the relay/resisitor is there from the factory, but I know my 255's would NOT work with the relay/resistor circuit in tact...

I had to remove the relay and add the jumper for my pumps to provide the correct pressure at idle & above....

I dont see any reason why a device that was made to operate at 12vdc couldnt operate at 12vdc all the time.... Unless the stock regulator cannot keep up (Which I dont use..)

-Dale

 

That seems like my new problem. when I start it up the pressure seems low by about 2 pounds. When I tip in on the gas it actually dips in pressure and runs real lean. And will continue until you get into the gas hard then it will switch on fine.

 

My thoughts, the fuel would heat up quicker, the pumps might wear out quicker, is the wiring sufficient? But I too use a jumper...

 

Ok; question for you guys using the jumper wire. What are you doing about fuel pressure at idle? Mine is around 60 with the jumper wire. But, that did fix the problem of it running lean/low pressure.

 

that did fix the problem of it running lean/low pressure

Good to see that you are making some progress

 

Hi Casey,
I remember reading an old post from about 2002 that was talking about problems running some 255 pumps and the resistor. As I recall some high volume pumps draw so much current that the voltage drop through the stock resistor lowers the voltage so much the pumps don't deliver enough pressure. I think this is your problem. What you might do is get another resistor and connect it in parallel with the original one so the voltage does not drop too low. The only time the pumps need to run at full voltage is when your boosting, otherwise it just causes extra wear and tear on the pumps.

Charles

 

Ive got an adjustable regulator on my truck...

-Dale

 

I wonder if you could just do away with the resistor all togeather?

I might give that a try, and order another resisitor to wire up in parrallel.

I am working on a fuel pressure regulator right now.