Ford 50Fi EFi engine: No power at high RPM untill and stop and restart.

[MasterGoa]

Hi all!

You may remember my thread last year about having a pair of these engines that would stay in FMEM
mode and run rough while guzzling fuel. So after fixing the issues, all has been well.

However, after my 14th outing this season, I started noticing something peculiar...(after over 800KM)

The right side engines sometimes cannot WOT. It runs perfect other wise, but
if I WOT it, the left engine will reach 4400RPM but the right one will simply stop
accelerating at a random RPM. Sometimes 3800, sometimes 3200. 2 weeks ago,
I was able to reach 4400RPM with both engines.

However, sometimes the max RPM is below planing speed, 2800 for example.
So I had an Ah-Ha moment: I simply stopped, turned the right engine
off, started it up again and went. Reached planing speed normally and WOT
came up to 3800RPM...

I changed the fuel pump relays in case, but the issue persists...

Any idea what could cause this?

Could it be the coil getting weak?

Could it be the high pressure fuel pump?
I am told the low pressure pump getting weak makes the engines have huge misses, which it does not.

I adjusted my throttle cables and they are still fine.
Did full tune up last year with platinum plugs. Starts on a 1/4 turn.

Any ideas?

Thanks.

MasterGoa

 

[MasterGoa]

Update: A fuel pressure gauge was used on the presta fuel rail fitting to determine
what is going on.

Using the manual, upon two pump pulses without starting the engine, you should get 39PSI +- 3PSI.
When starting the engine at idle, it should go down to 32PSI.
When revving at WOT, it should go back up to 39PSI.

This was tested with the normal engine and, even without load at the slip, should exactly
this pattern. Key on 2 sec, off and key on 2 second again. 39PSI.
Start engine, 32PSI, slowly rev engine by 500RPM increments and pressure
went slowly to 38PSI.

Bad engine did something different:
2 pump pulses showed 39PSI.
Start engine and idle showed 32PSI.
However, as I revved up the engine, the pressure went down.
At 4000 RPM, it went down to 27PSI...

So yeah, high pressure fuel pump is bad, but fuel pressure regulator seems fine...

Should I change both pump and regulator as a pair?

Cheers!

 

[Bondo]

Hi all!

You may remember my thread last year about having a pair of these engines that would stay in FMEM
mode and run rough while guzzling fuel. So after fixing the issues, all has been well.

However, after my 14th outing this season, I started noticing something peculiar...(after over 800KM)

The right side engines sometimes cannot WOT. It runs perfect other wise, but
if I WOT it, the left engine will reach 4400RPM but the right one will simply stop
accelerating at a random RPM. Sometimes 3800, sometimes 3200. 2 weeks ago,
I was able to reach 4400RPM with both engines.

However, sometimes the max RPM is below planing speed, 2800 for example.
So I had an Ah-Ha moment: I simply stopped, turned the right engine
off, started it up again and went. Reached planing speed normally and WOT
came up to 3800RPM...

I changed the fuel pump relays in case, but the issue persists...

Any idea what could cause this?

Could it be the coil getting weak?

Could it be the high pressure fuel pump?
I am told the low pressure pump getting weak makes the engines have huge misses, which it does not.

I adjusted my throttle cables and they are still fine.
Did full tune up last year with platinum plugs. Starts on a 1/4 turn.

Any ideas?

Thanks.

MasterGoa

Ayuh,..... Low fuel flows at higher rpms,.....

Check the Contents of the fuel filters for Water, 'n Crud,.....

 

[MasterGoa]

How do I check this?

 

[Bondo]

How do I check this?

Ayuh,.... Remove the filter, 'n pour it into a clear container, 'n Look at it,....

 

[MasterGoa]

Interesting development:

After receiving the fuel pump but forgetting the 3 o-rings to install it,
I used my time at the boat to do other stuff. Mainly replace the EFI relay,
the fuel pump relay and verify all vacuum lines with my trusty inspection camera.

Found two issues with the problematic engine: The high pressure fuel pump
electrical connection was very flaky, being pulled off by the weight of the
wire cluster... Un plugged the wire and re-routed it so that I would have slack
when it is hooked up to the pump.

Also, I found a kink in the vacuum line to the fuel pressure regulator so I re-routed
it as well...

Well, low and behold, I start the engines and go for a ride because of the really nice weather.

I trim the outboard and just let it rip: Both engines went up to 4500RPM without any hesitation.
Repeated runs at WOT and then 1400RPM trawling went perfectly... Did not have the GPS
hooked up but the pitot speedo said 48MPH... Was probably going 52-ish...

Will try again tomorrow on a longer ride and report back...