Fuel System Problem %e2%80%93 Diagnosis amp Next Steps

"From previous posts it looks

"From previous posts it looks like we have a fuel pump problem - need confirmation and next steps.

Last week we launched our 1989 Tiara 3600 Open, docked in Old Saybrook Ct at the mouth of the CT River. The boat has 7.4 Blue Water Mercruisers with 750 hours, ran well the last two years until Saturday when we encountered the following problem.

We went for the first cruiser of the year Saturday. The boat ran well for the about a 1-1/2 hr trip to our destination, 1400 rpm cruise. We stayed on a mooring for 2 to 3 hours. On the return trip we made it about 30 minutes before the port engine started to cut in and out then died completely. Was unable to restart the motor, cranked but would not fire.

Back at the dock we replaced both fuel filter / water separators, filling them with fuel. Engine started immediately then died again after about 3 minutes. Opened the fuel filters and about 1/3 of fuel was gone from each. Refilled filters and started engine again with the same results.

I have completed the following in my trouble shooting.

1. Checked fuel tank – ½ full, validated by gauge on tank and by running generator for 30 minutes.

2. From tank to engine we have the following – Racor S3232UL filter / separator, Mercruiser filter separator then mechanical fuel pump. Disconnected intake line from Mercruiser filter and inserted in to 1 gallon container of fuel. Tried to start engine with no result. Did not seem to pull fuel from container.

My thought is this is a fuel pump problem. It’s a mechanical pump mounted on the lower starboard side of the engine. What should be my next steps to determine if it is a faulty fuel pump? My tests seem to have ruled out any problem from the Racor filter to the tank.

Thanks for the help.
Tim"

"Tim
Have you checked the fu

"Tim
Have you checked the fuel pick up in the tank to make sure there is no restriction or blockage at the tank end ?
See if you can beg, borow or steal (forget the steal) a fuel pressure/flow gauge and compare the readings you get, to the manufacturers specs for your engines
Cheers
Peter C"

"Peter,

I was going to chec

"Peter,

I was going to check the tank pickup but they appear to be fixed to the tank - permanent (welded elbow is all I see). Based on that I tried the container of fuel on the intake side of the mercruiser filter. My thought was that if it pulled fuel I'd know the problem was on the Racor / tank side of the system.

Would I connect the fuel pressure tester to the pumps outlet?"

Does the pump have an internal

Does the pump have an internal filter held in place by a screw and strap on the bottom? What about the carb. filter screen? Change both before you buy a pump. Guy

"You have two (and that&#3

"You have two (and that's too many) filters BEFORE the fuel pump. That's bad news, for it can cause the fuel to vaporise, and pumps don't pump vapor (only liquid).

First of all, put a new pump in (and save the old one as a spare IF it doesn't help.) Next, relocate one of those filters to AFTER the fuel pump, and be sure your water separator/ strainer is just that, a STRAINER (coarse filtration) not a FILTER (fine filtration). You can buy different levels of filtration for that unit, so go with something nice and coarse, like 30 micron or larger. Use 10 micron AFTER the pump.

I constantly see people with all kinds of filters stuck before a fuel pump, people who are "shocked" when their boat suddenly won't run right. "But, it's been that way for years/ It came from the factory that way/ etc?" They were playing Russian Roulette with the pistons in their motors, and there were 5 bullets in the chamber!

Jeff"

"Thanks for the input Jeff.

"Thanks for the input Jeff.

I did some more research on my setup. The first filter from the tank is a Racor S3232UL (10 micron). The Mercruiser filter (35-802893T) mounted to the engine just in front of the pump is a 25 micron filter.

Now that I look more closely at our setup it does not make sense. Why filter with a 10 micron first followed by a 25 micron. I don’t think the 25 micron will do much good after a 10.

Yes, we bought the boat 2 years ago with this setup and yes it has worked fine until now.

Questions:
Is the 2 filter setup needed? Why not just use the stock 25 micron filter or is a 10 needed with today’s fuel environment (10% ethanol in CT).

Thanks,
Tim"