1997 4.3 Vapor Separating Tank?

[Technologic80]

1997 Four Winns Vista 278 with twin Volvo Penta 4.3Gi engines (Tbi) model 43FBPLKD. 160 hours.

Port engine is very difficult to start when cold. It will take lots of cranking and will catch, stall, catch idle at 200rpms, pop, stall. After 20 tries, it starts and stays running. After it finally starts, it runs absolutely perfect all day.

Ive replaced:
- Spark Plugs
- Wires
- Cap
- Rotor
- Low Pressure Fuel Pump
- Water filter/separators 4x
- Coolant temp sensor
- IAC
- Throttle position sensor
- Ignition module

It still does it. Its getting worse. At least last summer, it would just crank for a long time and THEN start. Now it requires a dozen or more times of TRYING to get it to even fire and then stall.

Ive checked for codes - none.

Hot restarts are perfect. Every time. The engine never stalls when warm.

After replacing all that, the ONLY thing I can think of being a problem now is the Vapor Separating Tank. Isnt there a float in it?

Would it matter that when I bought my boat, I had to fish pieces of impeller from the last owner out? Would a VST with a blocked water line cause vapor lock or something that would make cold starts difficult?

Im grasping at straws now... this is driving me insane.:mad-new::mad-new:

 

[dypcdiver]

Re: 1997 4.3 Vapor Separating Tank?

Vapor locks usually happen on hot engines and you say you don't have a problem when it is hot.
My thoughts are about sensors, but I see you have changed it. Next thing I would do is to swap the ECU's over as it sounds to me as if the TBI is not getting the signal to enrich the mix for cold starting.

 

[Technologic80]

Re: 1997 4.3 Vapor Separating Tank?

Swapped ECU's and no difference. That was the easiest thing my night consisted of, because then I figured "gee, maybe I should remove the HIGH pressure fuel pump and make sure the inlet screens are clear". What a freakin mistake.

Got the high press. fuel pump off, inlet screens squeaky clean. Took me 4x as long to reinstall. Apparently, there are two o-rings on the outlet side of the fuel pump. One was MIA and the other tore. Had to track those down to get everything reinstalled.

Is is possible for fuel pumps, when they start to go bad, to "stick"? Because it seems like when its cold, after its sat for a day or two, if I try to start it, it gives me grief and wont fire. BUT yesterday I tapped it 4-5 times with the plastic end of a screwdriver while a helper turned the key to start it and it started right up?

 

[dypcdiver]

Re: 1997 4.3 Vapor Separating Tank?

Question I have to ask is, did you try to start it before tapping with the screwdriver? You may well have disturbed something whilst checking for debris. Let's hope so.

 

[Technologic80]

Re: 1997 4.3 Vapor Separating Tank?

Question I have to ask is, did you try to start it before tapping with the screwdriver? You may well have disturbed something whilst checking for debris. Let's hope so.

I didnt try to start it before I tapped it with the screwdriver and at this point - I agree that maybe I did dislodge something because this morning it started right up and happily idled up and down as designed! :laugh:

Normally after sitting overnight it would be a bear to start - several rounds of cranking, starting, stalling, low idling (200rpms).

The screen to the high pressure fuel pump was squeeky clean but I gently blew it out with compressed air anyways and cleaned up the electrical connector. Also replaced all of the o-rings. When I removed the high pressure fuel pump, only 1 o-ring came out of the outlet side; there should be two. I dont know if it fell when I removed it, if it never existed, or if it dissolved and is somewhere else downstream. Either way, its got new ones now!

I also bought a new high pressure fuel pump yesterday to keep on the boat as a spare because "one day" one of my high pressure pumps is going to go tits-up and I dont want to be stranded. :embarassed:
Now I know how to change the pump, I could do it out on the lake in 10-15 minutes.