1992 Mariner 200 EFI, lost power

[Ricky_rich]

I have a strange problem with my engine. Sometimes I loose power, the 200hp feels like 5hp even with full throttle. If I put it in neutral I can rev the engine and think it sounds good. But with gear in there is no power. And then all of a sudden things are working, and I can get the boat to plane and go really fast. And then power is lost.
My guess is that engine is not getting enough fuel. Where would you start looking for the fault?

 

[dingbat]

View attachment 408423I have a strange problem with my engine. Sometimes I loose power, the 200hp feels like 5hp even with full throttle. If I put it in neutral I can rev the engine and think it sounds good. But with gear in there is no power. And then all of a sudden things are working, and I can get the boat to plane and go really fast. And then power is lost.
My guess is that engine is not getting enough fuel. Where would you start looking for the fault?

Sounds like your dropping a cylinder(s)

Compression, spark and fuel pressure test

 

[Ricky_rich]

Sounds like your dropping a cylinder(s)

Compression, spark and fuel pressure test

Testa done now with these results.

Compression
1. 8.2 bar
2. 8.5 bar
3. 8.2 bar
4. 8.6 bar
5. 8.1 bar
6. 8.5 bar

Fuel pressure
Only pump rinning 37psi
Engine running on idle 36psi
Engine running 2000rpm 34psi

Checked with a timing light that I have spark on all cylinderns. Spark advance on cylinder 1 looks good I think.

I can not read the fuel pressure any more for some reason. Maybe me meter gone bad. But engine is running good on idle. Would it be possible for the engine to run even without fuel pressure from the electric pump?

 

[Chris1956]

Check your fuel for water or other contaminate. drain the carbs and see what is there. Water is likely. If that doesn't get it, check spark on all 6.

 

[dingbat]

Would it be possible for the engine to run even without fuel pressure from the electric pump?

No… but a bad /failing high pressure fuel pump will cause all kinds of issues with an EFI

Fuel rail hold pressure at shut down or immediately go to 0?

Running a 10 micron fuel filter?
Cleaned the VST?

When is the last time you had the injectors cleaned?

 

[Ricky_rich]

No… but a bad /failing high pressure fuel pump will cause all kinds of issues with an EFI

Fuel rail hold pressure at shut down or immediately go to 0?

Running a 10 micron fuel filter?
Cleaned the VST?

When is the last time you had the injectors cleaned?

Yesterday I was out testing the engine, run fine for about 30 minuters, I was starting to think that the problem was gone, but no. Lost all power, could not get the boat to plane. 200 hp turned into 2hp.

A new 10 micron filter installed.
Fuel rail hold dont drop to 0 when turned off, have to check again how fast it drops.
I have not opened the VST, guess I should have a look at it.

 

[Ricky_rich]

Yesterday I was out testing the engine, run fine for about 30 minuters, I was starting to think that the problem was gone, but no. Lost all power, could not get the boat to plane. 200 hp turned into 2hp.

A new 10 micron filter installed.
Fuel rail hold dont drop to 0 when turned off, have to check again how fast it drops.
I have not opened the VST, guess I should have a look at it.

Missed the last question.
Bought the engine last year, and I have not cleaned the injectiors. Don't know if the have been cleaned in the post.