3208 Fuel pressure - idling problem
3208 Fuel pressure - idling problem
Men - i know a bunch of you have the 320HP 3208s...i have an issue that has steadily gotten worse...to the point that i must take action - hoping someone can help. When i bought the boat 7years ago, my port AND stbd engines would not hold fuel pressure / prime whenever the engines were shutdown and the fuel tank was less than 1/4 full. I'd come home from canyon fishing, shut down, and and hour later, i'd have to re-prime the engines to get them to start. Now - the port engine does the same thing when the tank is still 3/4 full AND at idle speed, the engine slowly looses fuel pressure until it stalls. This is a real problem when trolling offshore AND a dangerous problem around docks. At full cruise RPM the engine runs fine...but as soon as i slowdown it takes about 2 miunutes for the stuttering to start and maybe 2 1/2 minutes before the stall. Yesterday, i had a buddy stand by the hand prime pump to keep the engine going until we got into the fuel dock. Then - after the tank was totally full...the issue dissapeared again. I have replaced the entire intake side of the fuel system. Last year, my fuel tank was replaced (because of a pinhole) and while i was at it, i replaced all fitting and hoses. I pulled out the old racors and repalced them with the truck style double spin-ons (from Seaboard marine). Over the winter, i replaced a leaking throttle shaft seal on the governor of the port engine. I can't imagine where air could be getting in, except from the fuel return line / system. I remember some of you talking about check valves on the lift pumps and that this can cause similar issues - i think i remember charlie talking about putting a vice-grip on the return line to keep the pressure up until valve could be replaced. I'm going to call my guys at Ransome today, because i just can[t operate the boat like this anymore - but - do any of you guys have an idea of what the potential issue could be? Trouble shooting tips? Any ideas on why the fuel tank level plays an apparent role here? My one regret is that i filled the tank after yesterdays trip - so that will make troubleshotting a little trickier, because for whatever reason, the damn thing works great with a full tank. thoughts are really appreciated. I'm out of ideas on shere to go next, except maybe to pull out my pen and checkbook and let the pros figure it out...yikes!
Frank, There are 2 check valves in the ip that I had to replace. I'm the guy who had the channel locks on the return side to maintain pressure. If you use this as a fix don't. I only did it because I had a group I was taking to the canyon. When I got back I immediatly had them replaced. New upgrade for the ip's. Mike aka Stuart Lawrence
Mike Lawrence 81 sportfish 33' shot'n'beer 
When i replaced the tank i pulled the pickups out to check that they were OK. Pickups are heavyguage copper tubes soldered into the fittings that screw into the top of the tank. When i screwed all the fitting back in, i used liberal amounts of Rectorseal #5. However, there are no anti-siphon valves anywhere on the tank. Should there be?
Mike - thanks...i thought i read that here somewhere. I ultimately decided to have a fishing buddy standby the manual prime pump to keep the engine idling as we pulled into the fueldock. I was worried that crimping the returnline too much would cause over-pressure and create new, more expensive issues...and without a fuel pressure guage, i couldn't be sure what we were really doing. Is the correct fuel pressure 30 PSI? I assume these checkvalves keep the fuel pressure at a steady pressure then open at 30PSI (or whatever the correct value is) to allow fuel to return back to the tank? I'm reasonable sure the air is coming in from the return line, as at one point, when returning from a canyon trip, i left the tank empty and closed the shutoff values on the tank pickup..and the next day, i had the same problem. can really drive you nuts! Thanks Joe
I would remove the pick-up and pressure test it underwater and look for bubbles. That is how most tank builders test thier pick-up tubes. You definately need some sort of anti-siphon valve, basically it is a spring loaded ball valve. The spring could have corroded over time and now allows the fuel back into the tank when the fuel pump is not pulling that hard.
Thank God it's a Bertram 
If you think its pulling air, install a clear line from your racor to the secondary filter and see if there are any air bubbles. The pump should be putting out 30 psi. At idle it may be alittle low but once you start increaseing rpm it will go to 30. If not then you need to look at any internal wear in the ip. brass dust in the valley of the ip is a good indication that the ip may need to be rebuilt. Mike
Mike Lawrence 81 sportfish 33' shot'n'beer
well - tested out the intake side of the system. Basically shut the fuel valve on the tank, then used the manual prime pump to pull suction. Used the fuel restriction guages to keep track of the suction (i forget the actual bar measurment...but right on the "yellow" in the guage. Walked away for 2 hours. Came back...exactly where i left it. Given this test AND that i've replaced everything on the intake side of the system, i'm going to assume the issue is in the IP or lift pump. Guys at Ransome said there are 2 valves in the IP and one in the lift pump. ...just so i know how much medication i should take before i call Ransome, is replacement of these valves a major life event or relatively simple thing? Stu, i read your post that you remove the plate on the top of the IP to get to the values - didnt sound too horrible. ALSO - is there anything else i should look at and / or replace "while i'm at it?" Joe
joe I would measure the fuel pressure before I called Ransom. There is a plug just after the shut off solenoid. Remove and install a guage thet reads at least 75-100 psi. At idle you will see less the 30. Maybe 15-20 I can't remember. At 2000 or so rpm you should be about 30psi. Pump the fuel pump you use to prim. The reading will increase to 60 or more. If you can't push the pump handle in easy you may want to get the pump upgrade too.
Charlie 35 Bertram 3208 Cats