BIG 1996 Shamrock 220 WA Project

fisherlady2

Well-Known Member
Oct 5, 2016
953
162
Punxsutawney Pennsylvania
Most tanks have an anti siphon valve, after years of sitting it may be clogged. Other possibility is that the fuel lines themselves have degraded from sitting with ethanol fuel in them.. Try running the system on a portable tank to see if it draws fuel without problem. If it draws fuel we'll then the problem is in the tank end of the system, not your fuel pump end.
 

boataddict

Well-Known Member
May 19, 2020
163
32
Point Pleasant, NJ
I've already checked and I have no problem getting fuel from the tanks. I'm definitely dealing with an issue past the new fuel pump, which I'm certain is siphoning fuel.
 

Jonnydime

Active Member
Sep 7, 2021
38
1
Do you have a low oil pressure fuel switch. My 26’ has one that stuck off on me the other day. It shuts the fuel pump off if there is under 5psi of oil pressure.
 

boataddict

Well-Known Member
May 19, 2020
163
32
Point Pleasant, NJ
I have a suspicion that this part is the culprit. Seems like a second pump?
PXL_20210912_122709842.jpg
 

Jonnydime

Active Member
Sep 7, 2021
38
1
I know mercruisers have two pumps. A low pressure supply pump and a high pressure pump for the fuel injection.
 

boataddict

Well-Known Member
May 19, 2020
163
32
Point Pleasant, NJ
Well, I installed the new one and am getting good pressure to the TBI. Still no start though. Got a couple squirts from one of the injectors but overall still not really getting them to fire consistently. I'm thinking at this point I need to remove and rebuild the TBI, probably have a clog somewhere from sitting? What do you guys think? It's really the final thing I haven't replaced in the fuel system.
 

Bach Wilson

Well-Known Member
Sep 16, 2018
94
17
Are you certain they are supposed to be firing?

Do you have spark?

Are the batteries turning it over fast enough for it the TBI to sense starting?
 

deputyrpa

Well-Known Member
Supporting Captain
Aug 28, 2010
1,192
85
Fort Ann, NY
What is your voltage reading at the injector heads when cranking? It should be above 9 volts to spray.

IIRC, there is a screen in the injector bodies which may be clogged from sitting.

But first make sure you're getting adequate voltage from the ECM.
 
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