175 EFI stumbles

G

gonfishing

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Oct 31, 2011
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I have a 1993 175 EFI, Whenever go to full throttle the first time the motor acts like its loaded up and will just not go. Once i get going and it cleans out, I can run it the rest of the day with no problems. It will do this each time I take it out. It starts great and this is the only issue I'm having. Thanks for any ideas as to what could be causing this.
 
fisherman81654

fisherman81654

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Re: 175 EFI stumbles

gonfishing said:
I have a 1993 175 EFI, Whenever go to full throttle the first time the motor acts like its loaded up and will just not go. Once i get going and it cleans out, I can run it the rest of the day with no problems. It will do this each time I take it out. It starts great and this is the only issue I'm having. Thanks for any ideas as to what could be causing this.
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Could be a lot of things,I would first check timing with a timing light providing that you have already determined that you have good compression getting fuel and spark,could also be a weak fuel pump.
 
G

gonfishing

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Re: 175 EFI stumbles

fisherman81654 said:
Could be a lot of things,I would first check timing with a timing light providing that you have already determined that you have good compression getting fuel and spark,could also be a weak fuel pump.
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I'll give that a check. Thing runs like a new one after the first take off. Compression good, getting fuel, and spark looks strong.
 
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FLATHEAD MAC

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Re: 175 EFI stumbles

when you go full throttle the first time, has the engine been warmed up . started and FAST idled a few minutes befor going all out ????
sounds like its still COLD , then once warmed up after running, the stumble is gone :facepalm:
 
C

CharlieB

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Re: 175 EFI stumbles

Almost acts like the plugs are loaded up and has to clear out.

Verify what plugs and their condition.

Check the manual to ensure the TPS is set correctly, if slightly of it could be a bit rich.

Also verify temp sensor is reading correctly, wrong #'s here can cause a richer mixture until the motor is fully warmed.
 
G

gonfishing

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Re: 175 EFI stumbles

FLATHEAD MAC said:
when you go full throttle the first time, has the engine been warmed up . started and FAST idled a few minutes befor going all out ????
sounds like its still COLD , then once warmed up after running, the stumble is gone :facepalm:
Click to expand...

With the lakes I fish here, I may idle 1000 to 2000 ft before I can open it up. Motor is usally warm by then.
 
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gonfishing

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Re: 175 EFI stumbles

I have replaced the plugs and had the same issue.

I will have to check the manual for the TPS settings.

May have to change the temp sensor, I have always thought that it was loading up and after I go full throttle that 1st time it cleans everything out.
 
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