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-   -   Perkins 4108 motor getting air (http://www.sailnet.com/forums/diesel/63790-perkins-4108-motor-getting-air.html)

lbair 04-12-2010 07:57 PM

Perkins 4108 motor getting air
 
We have checked the fuel lines, the fuel filter, the return lines, got to the lift pump and found moderate fuel on the outside of it, all other leads exhausted but this...we ordered a lift pump today..... any leads or pointers!!!! The motor will run approx an hour then will accelerate up several times and then quits...

sailingdog 04-12-2010 08:31 PM

What was the last thing changed on the engine's fuel system??? As a general rule, if the engine was working previously and something was modified, upgraded, changed, and the engine isn't working properly, it is most likely something that you touched in the last modification, upgrade or change.

One thing to check are the banjo bolts and crush washers. If you overtightened the banjo bolts—that can result in a leak in the fuel system.

Another thing to look at is the fuel pickup tube in the fuel tank. If the pickup tube has a screen on it, and many come that way, it could be clogging up and causing the surging and dying.

Capttman 04-12-2010 08:32 PM

Very possible that the fuel filter gasket is not seated properly or the bleeder screw on top of the filter needs a new O ring

lbair 04-12-2010 08:37 PM

nothing has been changed since I changed the filters in the fall, re-changed the racor filter this wk, fuel tank was replaced in 05....and other leads???

sailingdog 04-12-2010 08:55 PM

Did you run the engine after changing the filters in the fall or before changing the Racor filter?

lbair 04-12-2010 09:21 PM

the motor was run at the dock before putting her away and then again when launched, until last wknd when was towed back to dock, then rechanged all filters, checked hoses, had a mechanic look at her and he checked back to fuel tank and moved towards the engine where he found a moderate amount of fuel on the lift pump.....

poopdeckpappy 04-12-2010 09:32 PM

Quote:

Originally Posted by lbair (Post 592268)
The motor will run approx an hour then will accelerate up several times and then quits...

Wow, you got an hour ??, I only got 30-45mins before my 108 did the same, changed the lift pump and it has run like a champ since.

lbair 04-12-2010 09:51 PM

thanks - thats reassuring to hear!! we hope to be sailing again this wknd

CarelessNavigator 04-13-2010 04:11 AM

Quote:

Originally Posted by lbair (Post 592268)
We have checked the fuel lines, the fuel filter, the return lines, got to the lift pump and found moderate fuel on the outside of it, all other leads exhausted but this...we ordered a lift pump today..... any leads or pointers!!!! The motor will run approx an hour then will accelerate up several times and then quits...

Air in the fuel system indicates a leak on the primary/suction side of the fuel system. A fuel leak is always going to be on the secondary/pressure side of the fuel system.

Symptoms of air in the system would be, hard starting, surge at idle or rough idle, engine misses under load, low power.

Symptoms of a leak would be, hard starting, engine misses under load, low power, excessive fuel consumption and of course fuel all over the place.

Good Luck!


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