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350 MAG MPI runs, for the most part. Need a little help

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350 MAG MPI runs, for the most part. Need a little help

Old 10-18-2020, 07:56 PM
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Default 350 MAG MPI runs, for the most part. Need a little help

Got my new to me 350 MAG MPI in and running. It fires up and idles great, but it has a hesitation/bog when you lay the hammer down to get on plane. If you ease into it, it will go. It also has a surge in the middle rpm range occasionally. Runs fine on the big end, turns a 21 mirage to the rev limiter through a 1.50 drive. Should I be looking at TPS, fuel pump, etc? I havenít had a chance to check anything yet, just looking for some help on the go to stuff on these engines. Hereís a few pics from todayís test ride.

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Old 10-18-2020, 10:56 PM
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Need more data.

What year motor and serial# (BUP style...inside joke).

Is the motor modified, crate motor or a take out?

What is the WOT rpm?

Has the ECM been tuned or tweaked?

An easy TPS check is to do a voltage sweep. KOEO (key on engine off) and read the TPS voltage from idle to WOT in a slow sweep. Should go from roughly zero to just shy of 5 volts without jumps or hang ups.

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Old 10-18-2020, 11:16 PM
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Originally Posted by Trash View Post
Need more data.

What year motor and serial# (BUP style...inside joke).

Is the motor modified, crate motor or a take out?

What is the WOT rpm?

Has the ECM been tuned or tweaked?

An easy TPS check is to do a voltage sweep. KOEO (key on engine off) and read the TPS voltage from idle to WOT in a slow sweep. Should go from roughly zero to just shy of 5 volts without jumps or hang ups.
serial is 0L316222 (I believe itís a 1998 model)
I bought it used, itís a take out from a boat that came off the trailer. Itís stock as far as I know but does appear to have maybe had a refresh because itís got new looking oil pan gasket. WOT itís turning 5000-5200 RPM. It runs strong on top end, getting there is the struggle
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Old 10-19-2020, 04:49 AM
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Start with the TPS voltage sweep. That is a relatively easy test. If that's normal we need to look at other stuff.

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