MAS?
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MAS?
My V-10 is hard starting. Takes 8-10 cranks to get it going. It starts out with low rpms, but then goes to normal idle Once it starts, it idles smooth. Once at running temp, it still runs smoothe. If I ease on the the throttle, no problem. Rpms go up without a miss. If I floor the throttle there is a hesitation for a second or two, rpms climb normally. This just happened all of a sudden. Air cleaner is stock and clean.
Fleet Mechanic
Joined: Oct 2017
Posts: 1,704
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From: Southwest Ohio
Need more info to help troubleshoot. What’s the mileage? Has truck been maintained as required?
Hesitation can be difficult to track down. Best to start with the cheap and easy stuff. First is to check for vacuum leaks. Vacuum hoses become brittle due to heat cycles and age. Check for cracked hoses or missing connections. Buy a can of starting fluid and spray it around the vacuum lines, one section at a time. If revs change, you found your vacuum leak. Replace the hose and see if hesitation is gone.
— Dave
Hesitation can be difficult to track down. Best to start with the cheap and easy stuff. First is to check for vacuum leaks. Vacuum hoses become brittle due to heat cycles and age. Check for cracked hoses or missing connections. Buy a can of starting fluid and spray it around the vacuum lines, one section at a time. If revs change, you found your vacuum leak. Replace the hose and see if hesitation is gone.
— Dave
Hotshot
Joined: Jan 2004
Posts: 19,760
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From: St Louis
It's unlikely to be the MAF sensor.
Usually doesn't work on these engines, the PCM is too fast an you'll never hear any difference.
Extended cranking times is usually associated with a weak fuel system (which would also cause hesitation upon sharp acceleration). A fuel pressure gauge is recommended for diagnosis, depending on the year of the truck.
Buy a can of starting fluid and spray it around the vacuum lines, one section at a time. If revs change, you found your vacuum leak.
Extended cranking times is usually associated with a weak fuel system (which would also cause hesitation upon sharp acceleration). A fuel pressure gauge is recommended for diagnosis, depending on the year of the truck.
FTE Chapter Leader
Joined: May 2002
Posts: 42,552
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From: Fraziers Bottom, WV
As indicated more information on the truck would be great. As projectSHO89 said this is indicative of a fuel delivery problem. Proper diagnostics are indicated and any stored DTCs would help.
Rod
Rod
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SomeDude451
1987 - 1996 F150 & Larger F-Series Trucks
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Sep 1, 2014 09:16 PM
