S/C Marauder Stumbling need help badly!

One of the vendors here can sell you a GT40 pump to replace yours. The tune will need to be adjusted. You can try without but be prepared for some stumbling as the car re-learns and go gentle on it at first.

But by the video you posted I don't think it's a fuel issue. I had a similar issue when my boost blew off a vacuum line. I could barely drive the car because it would drop in RPM's, stumble, and turn off. Or ignition problem across more than one COP (or power distribution) to make it stumble that badly.
 
Last edited:
RacerX said:
Actually, yes. It will work, but, there are parameters that are changed when you change to a new pump.


I stand correctied.

After my recent COP probs, I agree. It's a possibility at least!
Click to expand...

How can it be COP with fuel pressure all over the place?

I would also think a vacuum leak bad enough that it wount rev past 1500rpms would be easy to hear?

If the fuel pump was failing wouldn't the duty cycle be high?

It's not even my car and I'm getting frustrated just thinking about it.
 
03sport007 said:
How can it be COP with fuel pressure all over the place?

I would also think a vacuum leak bad enough that it wount rev past 1500rpms would be easy to hear?

If the fuel pump was failing wouldn't the duty cycle be high?

It's not even my car and I'm getting frustrated just thinking about it.
Click to expand...


Where have you seen fuel pressure data?



Here lets do something simple.

Would the car run like crap, then hours later or the next day run normal with a vacuum leak? Probably not.

If it was a massive fuel issue, then IMO it would be the same as above.

Now I have see COP's and/or the Ignition harness make cars stumble REAL bad one day, then drive fine for another 60 miles.

Check the computer at Ford to see if you are getting any no-fire codes on a cylinder, also check the problematic harness behind the drivers valve cover and firewall.
 
-Matt- said:
Where have you seen fuel pressure data?
Click to expand...


The fuel pressure data comes from me watching the fuel pressure gauge I attached to the rail. Essentially it sits at 20 PSI at idle. When I rev it up it never goes higher than 30 PSI.

So even if I had bad COP's dont I need to address the fuel issue first?

Thanks again.
 
FF1077 said:
The fuel pressure data comes from me watching the fuel pressure gauge I attached to the rail. Essentially it sits at 20 PSI at idle. When I rev it up it never goes higher than 30 PSI.

So even if I had bad COP's dont I need to address the fuel issue first?

Thanks again.
Click to expand...
with the info you have provided i would not worry about COP's. If you dattalog the car you should see the voltage at the pump, fuel pump duty cycle, and fuel pressure.
 
Last edited:
OK, out of curiosity, what does rail pressure spike at on average if you open the throttle all the way really quick and snap it shut? It should spike up in the 40+psi range for a split second as the injector pulse shortens and it takes the fp a sec to catch up by slowing down. Can you send me a log?
 
If I snap it open really quick its hitting a average of 30 PSI, never going a few PSI over 30 either.

What do I need to data log?
I have the Torque app for my phone and have a log from it, but I dont know if it has what people need to see.
Its too large to post here though.
 
I was thinking you had an sct tuner for some reason. You do have fuel pressure probs. No doubt there.
The fuel pump was upgraded? Who did it? Fuel sock jammed aginst the bottom? A clog somewhere in the lines?
 
FF1077 said:
The fuel pressure data comes from me watching the fuel pressure gauge I attached to the rail. Essentially it sits at 20 PSI at idle. When I rev it up it never goes higher than 30 PSI.

So even if I had bad COP's dont I need to address the fuel issue first?

Thanks again.
Click to expand...


Sorry i must have passed over that info while reading your thread.

Do you have a BAP?
 
I have a tuner that came with the car, I will look and see what brand it is tonight.

The pump was changed to the SVT Focus pump by the original owner.

I dont even want to think about a clog in the lines.

I do have a BAP.
 
FF1077 said:
I have a tuner that came with the car, I will look and see what brand it is tonight.

The pump was changed to the SVT Focus pump by the original owner.

I dont even want to think about a clog in the lines.

I do have a BAP.
Click to expand...


Can you hear the BAP running?
 
I highly recommend you to buy an sct tuner if you dont have one and offcourse have the car retune since you might not know how the previous owner got it tuned. Once you fix your problem.
Im gonna go on a limb and ask you to take the hat and FP assembly out, visually inspect everything, if all looks good grab a voltmeter and check for voltage at the FP. Thats the other way to do it if you dont have a source of dattaloging.
 
That should have the Trilogy tune on it. Looks like the one that would have come with your Trilogy kit from Jerry. Can't hurt to try it. If it's locked to another car, it will let you know.
 
Probably not the cause but maybe its the FPDM going bad? Ive seen electronics behave wierdly depending on ambient air pressure, humidity, and temperature.
 
You must log in or register to reply here.
Back
Top