just rebuilt yamaha 3.0. Starts and runs great cold then after about 30 min once warmed up it will not start without pushing gas pedal. then after a minute it runs ok. There is spark. Also new crank sensor cam sensor knock sensor engine temp sensor new fuel pump too. The issue of using gas pedal would seem to indicate what? fuel not turning off at injectors??? Any ideas?????Please///
92 sho mtx yamaha starts ok cold not warm without gas pedal
- Thread starter dawgsho
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92 mtx sho
I did check codes and got mass air flow 186 and 187. This could be a big part of it. Also went to check fuel pressure and had none at key on cold. That is new problem. Turned key off then on a couple times same result. Once started had about 37psi. Took off vacuum to pressure reg and it rose 4 psi. After idling a while with vacuum off regulator started bubbling some fuel. Put line back on. Pinched return line and psi rose about 5 ticks. Turned off key and immidiately lost all pressure. Did not turn back on and test hot yet because of the new problems. That is what I know so far. So maybe maf first of all. Thanks
I did check codes and got mass air flow 186 and 187. This could be a big part of it. Also went to check fuel pressure and had none at key on cold. That is new problem. Turned key off then on a couple times same result. Once started had about 37psi. Took off vacuum to pressure reg and it rose 4 psi. After idling a while with vacuum off regulator started bubbling some fuel. Put line back on. Pinched return line and psi rose about 5 ticks. Turned off key and immidiately lost all pressure. Did not turn back on and test hot yet because of the new problems. That is what I know so far. So maybe maf first of all. Thanks
Last edited:
Storm-Chaser
New Member
System should maintain fuel pressure for an extended period of time after the engine is shutdown, regardless of key-position. It may be posted here, do a search.
When you used the gas pedal, did you pump it or hold it to the floor?
When you used the gas pedal, did you pump it or hold it to the floor?
well, the "it won't start" problem is because there is no fuel pressure. there are 3 possibilities:
first, it could be the check valve in the fuel pump is bad and lets all the pressure bleed back into the tank.
second, it could be the pressure regulator that lets all the pressure bleed into the return line.
third, it could be one or more injectors that do not close that allow fuel to bleed into the combustion chambers.
given your description in post #4, I would start with a different pressure regulator.
first, it could be the check valve in the fuel pump is bad and lets all the pressure bleed back into the tank.
second, it could be the pressure regulator that lets all the pressure bleed into the return line.
third, it could be one or more injectors that do not close that allow fuel to bleed into the combustion chambers.
given your description in post #4, I would start with a different pressure regulator.
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