Engine hard starting / missing on 5.0 efi

J

jarrodsb

Member
Joined
Aug 1, 2005
RO Number
18531
Messages
36
Hello, 2000 5.0 EfI approx 640 hrs. This weekend it seemed to take a few more cranks on the ramp. Then it fired up four more times with no issues. After tubing the wife shut off motor with shift lever not in neutral. I went to start and the motor loped three or four times then stalled.( great with four kids on board). It would barely start then immediately shut down. In the past if it doesn't idle for a few minutes in warm water after running it - it wont start or is hard to start.
I pull fuel cooler drain plug and spray the fuel cooler with cold water, and I can hear it priming ( that usually does the trick) still no start. I played with the neutral cut out switch and made sure it's in the center of the notch and then it started right up.( then with it running I pushed the switch and it would idle down but not stall)
It ran great all day, then almost to the dock we stopped after a good run. After 15 min it started fine, as soon as I hit the throttle it had a miss ( almost a cut out).
Thanks for any help or direction. I not sure to think fuel pump or just a simple adjustment on the switch, but it looks like it's in the center???
 
Is this a MerCruiser? If so, which Drive, Alpha or Bravo? If it's a Volvo, which series?
 
So it's the Multi-Port Fuel Injection (MPI) 260-hp engine with 8 injectors? We had a 1996 MerC TBI (Throttle Body, 2 injectors) and it used mechanical "lift" pump to fill a Vapor Separator Tank which contained a high pressure electric pump. We replaced the high pressure pump when it turned out to be the lift pump. Symptom was it wouldn't re-start after being shut down hot. I carried a bilge blower wired to battery clips and used it to cool the VST and lift pump just below it.

Sounds like fuel starvation or vapor lock somewhere with a weak pump, bad pressure regulator, porous fuel hose, clogged filter.

Do you have a "high pressure" fuel pressure tester that you can put in line and see what it's doing?
 
Actually it's this with a throttle body and two injectors rated rb2@gr5t 240 hp. - at prop.
5.0L EFI GM 305 V-8 1999-2001
0L331631 THRU 0M299999
It has a electric fuel pump. I'll have to get a fuel pressure tester and check it. But
It does seem like vapor lock again (about the only issue its every had)
It just never surged like that before the stall??
I did replace it about 8 years ago so it may be time. A factory TSB recommends
Changing the fuel cooler now with it but that's another $200.
The cooler is all copper and not leaking. It seems like it can be cleaned??
I'll have to investigate that when I'm in it.
Thanks for your help!
 
Try letting the engine idle down before shutting off. Idleing down allows the engine to cool down. This is not an uncommon problem.
 
Sound like my 99 5.0 TBI Merc, I would try one that call "Shift Interrupted Switch" first before anything else, of course I did replaced fuel pump, clean out both injectors, replaced fuel siphon valve and had tried new MAP/TPS/ECU without any luck until I borrowed the service manual from my dealer and read thru every sensors and switches of how they works then tried $30 shift interrupted switch which happens to fixed my on going problem.
 
In getting an Interrupt Switch, the Alpha One's with Fuel Injection have an ECM, and their Interrupt Switch OPENS a circuit back to the ECM. The Alpha's with Carburetors have NO ECM, only an electronic distributor module. Those Switches CLOSE and create a temporary ground.
 
Thanks - I usually do idle down and let everything cool off before shutting her down - every since it happened several years ago and I was stuck. The wife hasn't driven in years and I forgot to tell her, so she shut it off early ( I was in the water so I didn't mind at that point).
Sorry I called it a neutral safety switch it was the " shift interrupter switch " That I was playing with. But from what I read it seems fine since it doesnt stall going into gear, and it shifts fine..... But I did read it should stall the engine - mine was only idling down when I pushed in on it by hand??
So I'm a little unsure about that - Im still trying to figure out if that's what made it hesitate on the last take off though??
 
Interrupt should happen coming OUT of gear IN the water. Any other time it's probably a bind in the lower shift cable or the vertical link to the gearcase.
 
best way to check the interrupt switch is using meter and check for Good continuity when the shifter is in neutral(switch closed) across two terminals, then with the meter stills hooked up, try pressing and releasing the plunger couple of time while watching the meter.
 
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