5.7 TBI possible fuel pump issue

[pursuit2460]

So, I was getting my boat ready for tomorrow and I go to crank it up. Its cranks just fine, no issues. But I started hearing a whine type noise coming from the fuel pump area. I placed my hands on the lines and I can feel the line has a small vibration, intone with the noise. I had a weird issue last time out. I took the boat out, no issues. Drove around for like 45mins or so. Docked at an island near by and hung out for like 1-1 1/2 hours. Went to start the engine and it would start and die. Got to the point that it wouldn't even start. Well I thought no big deal, I will just call tow boat in a little while and go back. Well, I tried it, it's been like 3+ hours now, and start right up. Like nothing happened. Is this a symptom of a fuel pump going out?

 

[QBhoy]

The odds on and usual favourite, would be bad fuel or water in the fuel. Have a look at the fuel filter. If you have any spare fuel in a can…rig it up so the fuel supply line can dip into that as a source. Fill the fuel filter with the fresh fuel too.

 

[pursuit2460]

Filter is brand new. No water in the old filter either. I just double checked and it's making a humming noise and the line going to the TBI feels like one of those electric toothbrushes.

 

[QBhoy]

Filter is brand new. No water in the old filter either. I just double checked and it's making a humming noise and the line going to the TBI feels like one of those electric toothbrushes.

Are you getting fuel spraying into the throttle body from the injector ?
Bad fuel may or may not be your issue perhaps, but if it was…the old filter being ok and a new filter in place won’t have any bearing on a very recent ingestion of bad fuel. Bad fuel only usually makes itself known, when things like this occur and not always noticeable until this point.
Alternatively you may have a fuel restriction somewhere in the supply side. If you’re still waiting, you could perhaps prove the fuel is available to the pump by taking the hose off or watching to see if there is fuel coming out the injector at the throttle body under the flame arrester, once removed.
I’d still be tempted to empty that fuel filter into a glass and see what comes out.
So is she branded an efi engine I presume ?

 

[pursuit2460]

So, the engine runs fine. Gets full rpms(4700), idles fine, starts right up, no issues what so ever. Today I just heard a weird whining noise that seems to come from the fuel pump and like I said the fuel line to the TBI/EFI has a small vibration. I have been reading and I have to check the anti-siphon valve from the tank. Could be starving the pump right now and wasn't before, who knows. Or it could just be the pump is going out.

 

[QBhoy]

So, the engine runs fine. Gets full rpms(4700), idles fine, starts right up, no issues what so ever. Today I just heard a weird whining noise that seems to come from the fuel pump and like I said the fuel line to the TBI/EFI has a small vibration. I have been reading and I have to check the anti-siphon valve from the tank. Could be starving the pump right now and wasn't before, who knows. Or it could just be the pump is going out.

Ah. Got you. Yeah it could be something like a restriction or it’s drawing air. But if the engine is running ok, seems strange if it was. Does it sound like it’s pumping air ? Rather than a steady tone ?

 

[pursuit2460]

The line going to the TBI feels like the line is aerated. Kinda feels like an electric toothbrush or beard trimmer type of vibration. And if I recall the pumps sounds weirder when priming up than before. But, yes the boat ran perfect last time. Only thing that happened last time was that after running around for about an hour, I docked the boat. Hour- hour&half later the engine started but died right away. Sounded like lack of fuel. Then after like 3-4 hours of just hanging out, I decided to try again. Started right up and ran perfect for about another hour that it took me to get back to the marina.

 

[04fxdwgi25]

Maybe check the anti siphon valve at the fuel tank, feeding the pump. Those valves are known to go bad causing fuel feed problems and pump will make noise due to starvation. Easy to bypass to test.

 

[pursuit2460]

So this morning I ran the pump with the fuel disconnected from the TBI.

 

[alldodge]

Looks like your pump is shot.
You should not be able to use those hose clamps and clear hose without them coming apart

 

[pursuit2460]

So the pump should have blown up that hose? Next question. Is a aftermarket pump any good. Mercury only sells a whole kit and it $860. I found a OEM cooler for $185 and all the OEM o-rings but the pump can't be found separate, only aftermarket. Also going to replace the pressure regulator while I am at it. Also $170 vs $50. Funny thing is that it's a Keihin NR-1, very common PR.

 

[alldodge]

Don't know your serial number but a TBI should be 30 psi and the hose clamped with that hose would would be leaking if not start to bulge. Can see from the pic that the hose is easy to fold over and crimp

No issue with after market fuel pump

 

[pursuit2460]

2000 5.7 TBI L635236. It did leak at the clamp very little and I was able to crimp the hose. It did bulge some. Any aftermarket you recommend or all are same. What about for the pressure regulator, also the same as the pump. Thanks for the help. New to I/O, always had O/B.

 

[alldodge]

Search for 861156A1 and others will show up

To do actual pressure check it would take a fitting 91-806901 and gauge
Pressure should be 30 psi

 

[pursuit2460]

Search for 861156A1 and others will show up

To do actual pressure check it would take a fitting 91-806901 and gauge
Pressure should be 30 psi
View attachment 376124

So I installed a new fuel pump, aftermarket and a new OEM fuel pressure regulator. Cooler was fine. cleaned it out. Went out this weekend. Boat runs perfect. Get to where I am going shut it down and if I try to crank it 20-30 minutes later, it will turn on but the rpms will fluctuate and eventually die. Crank it back, does it again and dies. On a 3 or 4 try it stays running just fine or if I give it some throttle to keep the revs up. Only thing I can think of is its getting vapor lock after turning it off. If I let it sitting for 2-3 hours it will crank right up, no issues. Cold, cranks perfect every time. Hot, stubbles to stay on unless I give it throttle then it idles to normal.

 

[alldodge]

Might be VL but need to find out if fuel pressure is correct

 

[pursuit2460]

Might be VL but need to find out if fuel pressure is correct

I am going to buy the fitting and check FP. Now if FP is fine, can it be something else other than VL? And I take it that if it VL there isn’t much I can do other than have the return fuel go to the tank vs the fuel filter. I’ve read that a lot of people hate the Cool Fuel system and have gotten rid of it and all problems solved.

 

[Lou C]

How about the crank sensor? These can cause trouble when the engine gets hot.

 

[pursuit2460]

How about the crank sensor? These can cause trouble when the engine gets hot.

Are you talking about the one in the distributor?