GT-40 Fuel Pressure Check

[DanielC]

There has been a lot of questions about GT-40 fuel pressure, and or driveability issues.
This is how I check mine.

[DanielC]

RE: GT-40 Fuel Pressure Check

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[jjgag60]

Fuel pressure

what is the third picture? where does you inline pressure guage go?

And last but not least. What computer do I want to look for if I want to plug it in to my Gt-40. I might get lucky and find one on CL or Ebay. When we tore down the block the mechanic said he could tell the motor was running lean, becuase the valves were white in color.

[DavidF]

RE: Fuel pressure

That is what the third picture is for, the guage connects to the shrader valve as pictured.

I would think the computer is PCM proprietary, so good luck...but who knows.

[DanielC]

RE: Fuel pressure

I have not needed to get a computer connection to my boat, Yet. I think the connection in the picture that I put to ground is a standard Ford connection. There is a possibility that a Ford OBD1 testor might plug into it, and pull codes.

[DanielC]

RE: Fuel pressure

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[DanielC]

RE: Fuel pressure

Keeping thread current

[DanielC]

Time to add a little more information to this thread.
The low pressure fuel pump should put out around 5 to 6 PSI, and more importantly, flow about a quart every 15 seconds.

There is a screen inside the low pressure pump body that catches the "big chunks" before they enter the pump.

[horkn]

I have not needed to get a computer connection to my boat, Yet. I think the connection in the picture that I put to ground is a standard Ford connection. There is a possibility that a Ford OBD1 testor might plug into it, and pull codes.

Looks like a standard Ford EECIV to me. PCM doesn't do anything to the ECM's from GM or ford. Well, except for eliminate the O2 sensors.

[DanielC]

I believe that when PCM got the engines, they actually got "industrial" engines intended for stationary applications, like irrigation pumps, log chippers, things like that.
They may have requested slightly different ECM programming from Ford. There are a lot of engine parts used in other applications, that PCM uses. Why reinvent something when a "off the shelf" item will work.
I do believe the FCC is a PCM designed and manufactured item.

[Tryathlete]

I'm of the opinion that the GT 40 engines are not industrial as they have GT 40
Heads.

[DanielC]

I believe they are industrial in the fact that they do not have the emission controls required for a car, or even an on road truck.

[chris196]

I know this is really old, but DanielC can you comment on what fuel pressure is at different times.
key on, not started - not mentioned in the manual
Idle - from gt40 manual I think this is about 31 +/-3
WOT - from manual 39+/-3

[DanielC]

The fuel pressure regulator uses manifold vacuum to cut back the pressure at idle. At idle the vacuum is high. Key on, engine off, manifold vacuum is low, and fuel pressure is high.

[chris196]

Daniel,
Thanks for the reply.
That's not what I saw. I saw around 10 psi.
I've been fighting a problem that has since changed over time.
Do you read ccfan? I have a thread over there on this:

http://www.correctcraftfan.com/forum...535508&#535508

this is my last entry with an electrical update. I'm currently not hearing the fuel pump pressurize:

I'm back and not with good news.
I was going to lake test the boat today, but decided to make sure everything was still running fine in my driveway before making the trip. No joy. Engine cranking and won't start.
I pay with the ignition and notice I am not hearing the fuel pump pressurize for that 1-2 seconds when I turn on the ignition.
I checked the voltage at pump and nothing, which makes sense.
I then took off the relay and checked the terminals there. I see just over 3V on terminal 30 & 85. Terminal 30 is coming from the 20/15 amp circuit breaker. I say 20/15 because the diagram has a 20, my boat has a 15. I've seen references of it being changed at one point by PCM.
Now, I check the voltage on both sides of my 15 amp circuit breaker and I see that same 3.1V on both sides. But, I see 12V on both sides of my 60 amp breaker. So, somehow between those 2 I'm losing voltage. Maybe a bad ground?

When I look at all the diagrams in the service manual, I do not see the 20/15 amp breaker involved in any other circuit, but I could be missing something there.

I'm assuming it's not the breaker itself as it shows the same voltage on both sides.
But, there is play in the breaker button. I can depress it slightly. That is not the case with my 60 & 12.5

When I previously had the boat running I did read what I believe to be proper fuel pressure numbers at the schrader valve.

And I guess the whole TFI thing was a wild goose chase.

Any thoughts are appreciated.