Vapor locking with FiTech, please help

[Hinmaton]

I had similar issues with FiTech. Mine turned out to be a bad injector. They are pricey but solved the problem.

I ended up swapping my FiTech with a Holley Sniper. Sniper isn't perfect but I've had minimal issues.

I’m starting to think about going this way.


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[Jfryjfry]

If the setup ran great for a long time and then started acting up, then something changed - it’s not heat control since it worked fine in the same conditions for years.

You should be able to hear the prime shot. When I had a Fitech (before switching to sniper) I would have to prime shot twice (an addl turning on of the key after the first).

But you diagnosing a zero fuel pressure situation is a good starting point. Even if it’s zero, it should build pressure when you turn it on I’d think.

 

[Hinmaton]

If the setup ran great for a long time and then started acting up, then something changed - it’s not heat control since it worked fine in the same conditions for years.

You should be able to hear the prime shot. When I had a Fitech (before switching to sniper) I would have to prime shot twice (an addl turning on of the key after the first).

But you diagnosing a zero fuel pressure situation is a good starting point. Even if it’s zero, it should build pressure when you turn it on I’d think.

When I had the accumulator in the engine bay, I could east hear it. And on cold starts I would do the same, cycle the key twice.
It is starting cold much better now.
Just a hot start issue.
It is getting pressure to the gauge (right at the throttle body), but I’m not convinced it’s sending the prime shot.
Does anyone know if all the injectors prim or is it just one? Wondering if maybe the one that does the shot is messed up?


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[Hinmaton]

In the past I’ve seen that the blades are fully dry when this issue occurs.


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[Hinmaton]

I just watched the throttle blades while someone turned the key.
I can hear the injectors clicking and doing their thing, but I see no fuel until the key is turned, and then it’s just one injector doing its thing until it catches, then the rest chime in.


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[Hinmaton]

I played with some of the settings to attempt to get more fuel at hot start, which seemed to work during a stall and restart event, but left for 20 minutes it won’t start at all unless I put fuel in the throttle body.
I’m thinking the issue is injectors or ECU?
Might be time for a new unit or something different?


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[73azbronco]

EFI 101, again.

What is the fuel pressure when you go to run position on ignition switch, not the crank position?

First step in analysing any EFI issue, fuel pressure.

 

[Hinmaton]

EFI 101, again.

What is the fuel pressure when you go to run position on ignition switch, not the crank position?

First step in analysing any EFI issue, fuel pressure.

40psi as of late, which seems low to me as this unit wants 58psi.
But when it’s cold and starts and runs normally, it’s also at 40 psi. As the engine warms the pressure builds to 60-70psi, sometimes 90psi.
I can’t quite figure out the PWM portion of this system.


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[73azbronco]

It should be operating pressure from the get go. FPR, or pump issue, or leaking injector, all things being equal. Cheapest to costliest.

 

[Hinmaton]

For what it’s worth, on the trail yesterday I came across across more symptoms that point in a few different directions.
While letting the truck idle parked (not wanting to shut it off), the engine began to surge slightly. Less like hunting for idle and more like surging with the pressure of the HP pump. Then it would do this while driving for a little bit.
Then I was having stumbling while maintaining a constant rpm, usually on the rise to a maintained rpm.
I brought up my TPS gauge display, and sure enough it would drop and then come back.
Then while driving on the road the engine lost power completely and I drifted to a stop. I popped the hood to check the fuel pressure and it had fuel pressure (40psi) at cranking, but would not start. I pulled the air hat to add some fuel, started right up, but when I put the air hat back on it dropped rpm significantly. I have a K&N cone filter with a pre filter bag on it, pulled the bag and it seemed to run fine.
3/4 of a mile later it died again next to my tow rig.
So, maybe I’ve got some all of the above going on.


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[73azbronco]

Fix the Fuel pressure first, air cleaner should not impact anything as much as you describe. Solve the low fuel pressure.

 

[gnpenning]

Any lines or wiring getting pinched with the air cleaner assembly?

 

[Hinmaton]

No lines pinched, but it sure runs better with the air cleaner off.

Interestingly, when I pulled it off the trailer it was running really rough, like it had a choppy cam, then it smoothed after driving up my driveway.

I pulled off the air cleaner, restarted it, the fuel pressure built to 60 and it ran smoothly.

Is it at all possible that a severe restriction in air would create high vacuum and the vacuum actuated pressure valve was dropping the pressure in the system?

Or maybe, the fuel pump just decided to work at this moment.


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[gnpenning]

Have you tried wiggling the wiring while it's running? Maybe even tapping the connections.

 

[Hinmaton]

Have you tried wiggling the wiring while it's running? Maybe even tapping the connections.

To the pump? Nope I haven’t, but I’ll give it a go.


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[gnpenning]

All the wiring pertaining to the fuel and ignition systems.

 

[73azbronco]

Wiggle the part the air cleaner screws on as well.