FUEL PUMP

[PAUL T.]

Hello to all........ I just changed my fuel filters and fuel pump to the napa 610 1051. My old pump worked fine but was 16 years old. My problem is that the engine will only run with the bleeder valve Half to Full open. I kept this valve closed with my old pump. Also I can't seem to get over 2600 rpm with the trany engaged. In neutral I can get 3100. I have a 3 bladed but didn't have this problem before. Also there is a fluctuation in the RPM of about 100. Any IDEAS THANX.......PAUL

[PAUL T.]

RON...... Thanx for the quick reply, My boat is #766, 1988, MP25XP It would be an awful coincidence if my injecter pump went out at the same time as the pump change. I guess anything is possible. Do you think the new pump has the same specs as the old. Do you think there could be air in the system? I will try your suggestions. Thanks again RON..... PAUL

[Tom P, IMPULSE #233, '86]

Paul,

I'm with Ron concerning the installation of the old pump and give it another try...

If you cannot run without opening the bleeder, my guess is the pressure shutoff valve in the new pump is either set too low, or is faulty and not providing enough pressure; the pump should have an internal pressure sensor that shuts the pump off when X pressure is achieved, so the pump does not run all the time.  In your case it sounds like when the bleeder closed, the pump is not producing enough pressure or volume...Having the bleeder open causes the  pump to run all the time and get fuel (pressure and volume) to the engine...

Concerning the max RPM's; maybe even with the pump running (bleeder open), the pump still isn't getting enough fuel (pressure/volume) to the engine to achieve max RPM's...

I'd definitely swap back to the old pump and give it another try...

If no change, then start taking the filters off and make sure they are installed correctly and are not dented; a dent in the outside of a filter could also restrict flow...And make sure the old filter gaskets came off with the old filters; ie gaskets are not double stacked making a poor seal (allowing an air leak or fuel leak).  

A final thought; on my last boat I spent a lot of time and money chasing an RPM issue when the real problem was a dirty prop...Before you do anything too drastic, I'd also go over the side with a scraper and make sure the prop is clean; just a little growth can make a BIG difference...

Good Luck!
Tom

[PAUL T.]

TOM......Thanx for the informative reply. My problem does sound like a fuel starvation problem. Tomorrow I will put the old pump back in. I guess this proves that if it aint broke leave it the heck alone....... I will keep you posted Thanx Again ........PAUL

[PAUL T.]

Greetings....... I found the reason for my fuel starvation problem. The tank had so much crud in it the elbow in the pickup tube and the shut off valve were almost completely blocked, also the inlet on the RACOR was almost completely blocked. I was quite surprised.... the bowl always looked so clean. The boat is a 1988,I've had the boat for 2 years now. I removed the tank and am repacing with a new one. I found no pickup screen in the old tank. My search for past info yielded a wealth of usefull information. Thanks for all of your help......PAUL