1995 Merc 200 XRi - serial # OG178803
The motor is on a 19' bass boat. Have been fighting multiple effects throughout the spring and could use some help finding root cause.
I initially had an issue where boat would only idle and would die while running. My mechanic initially found a cracked mid-section housing and blown exhaust gaskets which he replaced with a mid-section he had from a 175 XRi and fresh gaskets. He also said I had two cracked coils that he replaced. I noticed an immediate improvement in low-end power but still had the issue where the boat would shut off after running for a minute or so.
I took it back and he found deteriorating fuel lines. I was surprised since I had replaced them about 6 years ago with ethanol-approved lines, but he showed them to me and they were indeed bad as the inner liners were separating from the housing but not brittle/breaking. He replaced all fuel lines but DID NOT rebuild the pulse fuel pump or replace the water separator filter since I had done those about a month prior. The boat performance immediately improved. The first 4 or 5 attempts to get on plane were full power but on the next attempt and all subsequent attempts (consistent for last 2 - 3 trips) it hesitates when getting on plane. It seems to bog like its down on power and then it will finally kick in and go once it starts to get to fall over onto plane. Once on plane it seems to be fine at mid and high rpms - runs great at around 5500 - 5600 rpm. One point of note is it always hesitates when motor is down for launch but doesn't seem to do it if I power load on the trailer with motor trimmed slightly above level - not sure if that is relevant but wanted to note it. Also wanted to note that 1st crank of the day it always starts up and revs strong. Subsequent attempts to crank I usually find the primer bulb empty and even after pumping it is difficult to start and acts like it is starving for fuel. Seems to crank better if motor is slightly above level trim but I always pump bulb, wait for 10-20s after key turned ON, and then try to start. It usually acts like it is starving for fuel. I had some time this weekend so I decided to do some troubleshooting myself.
I performed a fuel pressure test and found a few things. Results are below:
- key in OFF position with bulb firm: 0 psi
- key in ON position with electric pump running (~20 s): 39 psi
- 10s after Epump turned off: 15 psi (I'm assuming this is incorrect so something isn't holding pressure - true?)
- 20s after Epump turned off: 10 psi
- idle speed (~750 rpm): 36 psi
- under accel (up to 2000 rpm): 36 psi
- 15s after shutdown: 10 psi (again I'm assuming this is a problem)
- 30s after shutdown: 5 psi
- 60s after shutdown: 0 psi
I removed the final filter and confirmed that it was clean. I also removed the fuel pressure regulator but noticed the small filter that is supposed to be in that regulator isn't there. Don't think this is my problem but I'm assuming that needs to be there - where can I get one? I then performed the fuel pressure regulator test where I turned the key with the regulator held into a glass jar and it shot fuel when key was on and immediately stopped with key was turned off. Fuel looked like good/clean oil/fuel mixture.
I do have a pulse fuel pump rebuild kit and water separator filter on order but delivery has been delayed. I plan to install those to rule out any residual effects from the bad lines as it should have been done all at once from what I'm reading.
Can someone please advise what I should do next? I'm thinking the fuel pressure loss after the Epump turns off and immediately after shutdown is indicative of the issue.
I appreciate any help you can provide.