Re: Testing a mechanical fuel pump
It is a marine pump as far as I know. Double diaphragm AC Delco if I remember correctly. This is an old style set up that has a sight glass instead of an overflow hose.
I haven't laid eyes on the pump in a few days, so I may be remembering a port that isn't where I think it is. The grey matter in my head ain't what it used to be.
Here's the best description of my problem. If I took my other boat out taht has a trusty old Johnrude V4, wound it up to WOT, and momentarily hit the choke switch every few seconds, I would get near identical results to what my 302 is doing. There is no violent shaking like there is a miss, no popping, no snapping, etc.
What put me on this track (i've had this issue for a while, but I almost never run hard enough for it to be an issue), I ran across a post from a jetboat owner who had what sounds like the same problem out of a Ford BB. He went through the ignition from top to bottom and replaced everything and got nowhere. On a hunch, put a gauge on the fuel line and was only getting 3-4 psi. There were no visible fuel leaks.
The pump on mine was on the boat when I got it 6 years ago. This problem started season before last. There was an old pump under the front seat tho..... If it were a car, I would throw a cheap pump on it to test, but a marine pump is $125+.
Since this set up has a molded steel line between the pump and carb, I was trying to figure out a way to test the pressure without disturbing it. looks like my best option though is to get a couple feet of rubber fuel line and a T so I can plug in a pressure gauge for a bit.
It is a marine pump as far as I know. Double diaphragm AC Delco if I remember correctly. This is an old style set up that has a sight glass instead of an overflow hose.
I haven't laid eyes on the pump in a few days, so I may be remembering a port that isn't where I think it is. The grey matter in my head ain't what it used to be.
Here's the best description of my problem. If I took my other boat out taht has a trusty old Johnrude V4, wound it up to WOT, and momentarily hit the choke switch every few seconds, I would get near identical results to what my 302 is doing. There is no violent shaking like there is a miss, no popping, no snapping, etc.
What put me on this track (i've had this issue for a while, but I almost never run hard enough for it to be an issue), I ran across a post from a jetboat owner who had what sounds like the same problem out of a Ford BB. He went through the ignition from top to bottom and replaced everything and got nowhere. On a hunch, put a gauge on the fuel line and was only getting 3-4 psi. There were no visible fuel leaks.
The pump on mine was on the boat when I got it 6 years ago. This problem started season before last. There was an old pump under the front seat tho..... If it were a car, I would throw a cheap pump on it to test, but a marine pump is $125+.
Since this set up has a molded steel line between the pump and carb, I was trying to figure out a way to test the pressure without disturbing it. looks like my best option though is to get a couple feet of rubber fuel line and a T so I can plug in a pressure gauge for a bit.
