Losing fuel pressure only at idle

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jonboatboy

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Jan 18, 2014
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Location
Bowling Green, Kentucky
Well after a few weeks of sitting in my garage I took the family out on the lake on Mother's day. This was my old lady's idea. I was in shock. I rarely use my boat because my buddy I fish with has a bigger boat and it keeps wear off mine. I put it in and idled around until they made it to the dock for pick up. Idled out of the no wake zone and put her up on plain and rode a couple of miles. Pulled into another no wake zone and after a minute or so the motor dies. My first thought was to check the bulb. It was mushy. Pumped it up firm again and motor fired right up. All day it was a on going process. Got it home and started checking my fuel hose, connects, and tank to see if maybe the line was sucking air. Unhooked the fuel hose from the motor side and the fuel connect was hissing when I pumped the bulb. I had a extra so I replaced it and assumed that's where the problem was. Took it out last night and put in. Left it idling while I parked the truck. Did great idling and WOT. Then when I went to idle out of the pocket it started doing it again. Idle fine until the bulb would turn soft and I'd pu.p it up and it'd do fine until the bulb goes soft again. Brought it home and started checking stuff out again. It died the first time on muffs and after a few min of checking connects, ect. I started it back up and it idled fine. No cutting out and didn't die. I'm stumped. Any and all advice or criticism is appreciated.
 
You might want to check into replacing the diaphragm on your fuel pump. Mine does a similar thing and that is what I was told to purchase for mine.
 
Might be because since my last post I went got a new hose and primer bulb and two new spark plugs and it got a little better but still dies. I'm not having to pump the bulb anymore but it don't want to idle good. I asked the mechanic at the dealer I bought the boat from and his advise was the parts I replaced. Is a fuel pump rebuild expensive? I have OLD about my car and truck and my boat. Drives me nuts until their fixed. I also bought two brand new fittings. I was thinking it may need a tank but that's only because I'm trying to convince myself it's not in the fuel pump or carbs. Thanks for replying so fast.
 
Only way I know of for that bulb to get mushy is to have a leak in the fuel system. It's possible that the leak is coming from the fuel pump but I'd suspect the problem to be between the pump and the fuel that's inside the tank. You've replaced the fuel line and bulb, but what about the connectors on the end of the line? Have you checked the fuel pickup line inside the tank and the fittings on the tank?
 
Well I just dropped the boat off at the shop. We did a compression test and both cylinders had 130psi. The motor originally came out with the VRO but was plugged off and done away with. They seem to believe that since my fuel pump is meant to be used with the VRO then it may be my problem or its in the top carb. I will keep you guys posted.
 
UPDATE! Just went and picked the boat up. It idles better and seems like it's right. Mechanic said he pulled the top carb off and inspected it for trash but found nothing. He cleaned the carb and adjusted them. First thing I did was put the muffs on it and let it idle. Pulled the top plug wire off and the motor died. It didn't before so I was just checking. Going to try it out this weekend.
On another note while I was driving home with the boat I noticed the rpms on my truck became erratic so I slowed down and sure enough it had lost overdrive. I've had this transmission rebuilt twice in the last two years by two different people and here I am again. The first time I got about 6000 miles out it and it's about the same this time. I never drive it unless it's pulling my boat, lawn mower, or moving stuff. I just keep my head up and tell myself there's people out there who have it worse then me.
 
I did on the interstate but my trucks a 97 Chevy 1500 crew cab 4x4. It should handle my 16ft aluminum boat easy. I put a transmission cooler on it when I had it rebuilt the first time. Took the boat out today and it done a little better but it still is starved for fuel. It idles kinda rough and dies after a while and if I don't keep pumping the bulb it dies at idle and WOT. I can't win for loosing. I hope I ain't the only one with bad luck.
 
Rebuild the fuel pump, seen this fix that issue several times over. If you can pump the ball and keep it running at idle but it won't pull enough to do it on its own at low idle it may be the internals are getting mushy. Under more demand it is pulling like it should but lower it is not making enough fuel move.
 
I think your right. It's getting worse and it wouldn't run wide open without me pumping it. I was going to run up river in the lake but was scared of getting stranded.
 
I had to rebuild the fuel pump on my old 99 Johnson 40 hp. I had replaced the VRO pump with a regular fuel pump (new) about 5-6 years prior but I think the ethanol in the gas is wearing out the fule pump diaphragms. The rebuild kit was around $50-60 and solved my problem.
 
Just got the boat back and it seems to be doing better. The VRO had been taken off the motor when I got the boat and they had just plugged it off. They put a normal manual fuel pump on it and I believe it took care of it. It idles better and runs a little smoother. I think I may need a new gas tank because when I filled it up it was swollen real bad but after venting it went back to normal. I have never seen a gas tank that didn't swell especially in the summer heat. Even the ones for my lawn mower look like balloons sometimes. If I got a new one would it make any difference or is there a reason to replace? I know a lot of people talk about it on here.
 

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