454 MAG MPI issues. Won't rev under load.
04-19-2014 | 10:40 PM
#31
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From: Wilmington ,North Carolina
28- How much for the VST? Also, I pulled the line of the fuel tank and the barb had a check ball in there, the boat orig had a carb 454 in it, is it ok for a MPI Mag motor to have this or should I swap to a normal barb?
05-05-2014 | 08:16 AM
#33
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From: Rapid City SD
You really need to put a scanner on it to see what is happening & what the timing is under load. Although if it is a fuel problem, the scanner isn't going help. Have you put on a fuel pressure gauge to see what that is doing under load? I would sell the VST to you for $100 + shipping just to get it off the shelf collecting dust.
05-26-2014 | 12:04 AM
#34
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From: Wilmington ,North Carolina
Ok, put a new (used) VST on along with a new MAP sensor
And ignition control module (the old one was nasty). She got up
Very slowly and did plane out and run decent. When I pull it out of
Gear the idle surges to about 1400 and back down until I turn it off
And back on. This seems to be a bad IAC to me. My question is, can
A bad IAC cause the boat to run poorly?
And ignition control module (the old one was nasty). She got up
Very slowly and did plane out and run decent. When I pull it out of
Gear the idle surges to about 1400 and back down until I turn it off
And back on. This seems to be a bad IAC to me. My question is, can
A bad IAC cause the boat to run poorly?
05-16-2019 | 09:29 PM
#35
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97 Baja 454 magnums fuel injection
My one engine idle rev up in neutral great , under load it was starving for fuel would not rev past 2500 rpm all it was ,was the spark plugs, also there’s a belt that turns the fuel pump was worn out replaced and tightened good fixed the problem
05-17-2019 | 09:16 AM
#36
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From: Henderson, NY
Sounds like my old symptoms, fuel issue, vst probably, check the high pressure side while under load with a gauge,engine might be starving for fuel
Last edited by camptappakeg69; 05-17-2019 at 09:19 AM.
05-17-2019 | 11:16 AM
#37
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Video settings have been switched to public. I did drain the fuel and replaced with new fresh gas, as well as new plugs. I will check the distributor next for corrosion.
I did notice that the outdrive reservoir oil level was low, but I don't think that this symptom would be caused by guardian mode.
It would be helpful if someone could comment on whether guardian mode would produce a momentary drop in revs or a constant drop.
The fact that the engine won't produce the power to get over about 2,700 RPMs, also makes the guardian mode scenario unlikely and a fuel or electrical issue more probable.
Thanks
I did notice that the outdrive reservoir oil level was low, but I don't think that this symptom would be caused by guardian mode.
It would be helpful if someone could comment on whether guardian mode would produce a momentary drop in revs or a constant drop.
The fact that the engine won't produce the power to get over about 2,700 RPMs, also makes the guardian mode scenario unlikely and a fuel or electrical issue more probable.
Thanks
05-21-2019 | 01:39 PM
#38
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From: Michigan
I see that this is an old resurrected post but my motor was doing the exact same thing and after going through and replacing the vst, hp fuel pump, IAC, distributor, cap, rotor, wires, plugs etc... it turned out to be the fuel pressure regulator valve.
