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1995 GT 40 Start Problem |
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craigmeade 
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Joined: February-02-2020 Location: Florida Status: Offline Points: 32 |
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 Topic: 1995 GT 40 Start ProblemPosted: May-06-2024 at 2:30pm |
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95 SN196 with GT40. Will not start. Timeline: Engine all tuned up and running normal this season. After the first 3-4 sessions, I began having a problem starting the boat again while flushing it in my driveway (I ski in brackish water). While the engine ran normal during skiing, turned on and off several times, after the ~1.5 hour delay and starting in my driveway, it would fire up then stall, not holding idle. I was able to clear this by disengaging the trans and giving it a little gas, then it idled normal. Saturday I warmed it up in the drive way and changed the oil, no problem. on and off about three times. This morning our early ski plans were trashed because we could not start the boat coming off the trailer. It would do a quick fire up, but would not hold idle, and now disengaging the trans and giving it a little gas did not help. I'm thinking it is a fuel pump problem, appreciate feedback on how to diagnose!
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11115 |
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Posted: May-06-2024 at 8:24pm |
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A fuel pressure gauge for fuel injected engines will come in kinda handy.
A test kit from Harbor Freight is pretty reasonable and has the adapter for the Ford test connection. With the gauge hooked up to the test connection on the fuel rail, if you turn the key to the Run position, you should hear the pumps run for 2 or 3 seconds and then shut off because the ECM knows the engine isn't running. During those few seconds, the pressure should come up to 39 psi plus or minus a few pounds, so about 36 to 42 psi. You might have to cycle the key a couple times to get a good representative number. That 39 ish number will change if the engine is running. At idle speed it will be about 31 plus or minus 3 psi if you get the engine started When driving it around it'll vary between 31 and 39 depending on engine vacuum. I'd check your tether switch to be sure it's in place correctly and check fuel pressure as a starting point. If you don't hear the pumps at all when the key is turned to Run, then it's time to check the 2 relays near the ECM and the 12.5 and 20 amp breakers on the back of the engine that supply the 2 relays and the ECM. You need 2 good breakers and 2 good relays for the engine to run, so you cant just swap the relays with each other. Replacing both relays at the same time is the best way to do it The 12.5 amp breaker is for the ECM and the 20 amp breaker is for the fuel pumps. The ECM relay supplies power to the ECM and also supplies the control power for the fuel pump relay so both breakers need to be shut. and both relays need to be good for the pumps to run. The manual shows a 20 amp breaker for the pumps but later ones were 15 amp. Your 95 is probably a 20.
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craigmeade
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Joined: February-02-2020 Location: Florida Status: Offline Points: 32 |
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Posted: May-08-2024 at 10:04pm |
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finally took the time to do what i should have done earlier: looked over the electrical connections to the fuel pumps. i found a broken clip on the connector to the HPP that allowed it to loosen and separate. I taped it back in place and all is good! I wish they were all this easy....
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11115 |
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Posted: May-09-2024 at 7:18am |
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Since you got off cheap and easy, now's the time to spend a little bit for a fuel pressure tester so that next time there's a problem, you'll be able to check pressure real easy as part of your troubleshooting
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craigmeade
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Posted: May-09-2024 at 10:02am |
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Funny you should that because I already had my new harbor freight fuel pressure gage in hand when I found the broken connector! On another note, any idea where I can order a new connector? It looks to be part of a harness so not readily available on the usual parts sites I shop on.
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11115 |
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Posted: May-09-2024 at 10:41pm |
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No guarantees, none at all, well maybe a slight one, but for about 9 bucks, I'd give the connector in the link below a shot. It may look a little different but it fits a bunch of pumps that cross reference to your original that should look like the one in the picture.  If you get one, just promise to post here whether it works or not for your 95
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