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1997 Mercury EFI starting issues... HELP

V

VAbass

New member
I have a 1997 Mercury 150 EFI that will not start when it's cold. I can spray a gas/oil mixture into the cylinders and it will fire right up and pur like a kitten. After getting it started I can turn it off and on all day with no more issues. Once the boat sets for a day or two it goes back to not starting when cold again. I have replace the air temperature sensor. Check my fuel pressure. every thing seems fine. Any hints to what it might be before I drop $100.00 for a service center to tell me what it is? Thanks.

Floyd
 
It started last summer with the guy that owned it before me. He passed away last fall and I bought the boat from his step son to help his mom out with money. The steps to start it are as follows: 1) Remove a spark plug and spray a gas/oil mixture into the cylinder and replace spark plug. 2) Start the motor. It runs great after it starts and runs great all day even after you cut the motor off you can re-start it with no problems. But after the motor cools completely down say after a day off setting it won't start again unless you repeat the steps. I've replaced the fuel line and primer ball. Cleaned the tanks. The fuel pump works. So I'm lost from here. Oh and I did a compression check and thats good.

I was told it was the air temperature senor. Nope that wasn't it. Then I was told it was carbon build up so I bought power tune cleaner made by Mercury and sprayed into air intake while motor was running. Nope that wasn't it either.
 
Check your fuel pressure. Maybe it's not getting a cold start fuel pulse. Not familiar w/EFI but if it works all day after starting it your way there is a cold start fuel issue.
 
guyjg,

I don't have access to a fuel pressure gauge. I took the line loose and ran it to a gas can. When I turned the key on it looked to be pumping o.k..

Chris,

I can only assume it is. When I run the seriel #'s it comes back as fuel injected.
 
Just checking. Depending on where you live, You can get a fuel pressure gauge from Harbor Freight or Sears. You will need a Fuel pressure gauge to diagnose this.
 
Hey Chris,

I read somewhere that a sensor would cause a cold start problem but in warmer temperatures (summer) the motor would start. So I used a heat gun on low to warm the area's around the intake up to a summer time temperature and the motor fired like it should. I bought a fuel pressure tester this morning and the pressure is 34. I then pulled the boat out and hooked it to the water hose. I started the motor using the steps mentioned before (spraying gas/oil mixture into cylinder). Again the motor started right up. I stopped the motor about 10 seconds into running to keep the heat down in order to see if the motor would start again which it did. I'm dropping it off tomorrow at a service center to have it diagnosed.

Floyd
 
Other than the fuel pump what could cause this? I don't understand the whole not starting when cold unless spraying gas/oil into the cylinders first. And why would it re-start with no problem after getting it started the first time? Sorry for asking so much but I'm running out of funds and would really like to fix this myself rather than paying someone else.
 
i would fix what i see broke which is low fuel pressure....a shop is going to do it anyway and charge you good money...they are going to either rebuild the pump with a kit or replace it...
 
What do you think about this? I took the fuel pressure regulator off the other day. I noticed that the o ring that goes between that and the VST looked odd. I put it back anyway and re-installed the regulator. I noticed that the o-ring seemed to not seat the two together correctly. Sounded and felt more metal to metal to me. Would this not seating correctly cause the low fuel pressure issue?
 
O.K. I think I'm on the right track. I got the fuel pressure up to 39/40 from the 32/34 that it was before when cold. I cranked the motor and it fired. After a little more tinkering I got the motor to start for a couple seconds. I also sprayed Quicksilver power tune into the fuel rail and blew it out. This seemed to help. I did'nt think about lubing the o-rings. I'm going to go over it one more time double checking everything and see what happens. Thanks for everyones help.
 
Help!!!!!!!!!!! new problem........ Here's the deal.. I took the boat Sunday before last to the lake for test and tune. Everything worked great. Boat ran like a champ. This past saturday I was fishing a tournament at the same lake. I stopped and put gas in the boat at a station I normally don't use. Got to the lake started the boat and let it run for a little bit. When launch time came I started the boat, they called my number, the boat got on plan fast as ussual and ran great to my first spot. I fished for about a hour and decided to move. The boat then would not get on plan for nothing. Put it in netural and cleared the engine and noticed a excessive amount of smoke. It cleared and the boat ran fine to the next spot. After fishing for a while I went to move and it did it again but this time it would not clear up. I checked for water and trash in the fuel but found none. Your thoughts on this would be appriciated. Thanks.

Floyd
 
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