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Idle Surge and Power Loss HELP

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smithder

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"I have a 1996 5.0 Fuel inject

"I have a 1996 5.0 Fuel injected engine that is surging when idling. I have checked for vacum leaks tested the TPS voltage at idle, cleaned the throtle body and the IAC. It seems to help if i advance the timing a little. Fuel pressure is good at 40 psi. I also seem to have have lost some power at W.O.T. I can only get about 4000 rpm out of it with a 19 pitch prop. The boat is a 19' Four Winns cuddy. The motor is rated for 4400-4800 max. It came with a 21 and a 19 pitch prop. Seems like I should have more rpm lightly loaded with the small prop. I could not plane out with 5 people on board unless I moved folks toward the front."
 
"I had a suging problem with m

"I had a suging problem with my 96 5.0, What happen when I ran on battery 2 the motor would surge, if i switched to battery 1 it would run fine. it has been this way since I bought the boat. I think the battery 2 is just a starting battery, after it starts I switch back to battery 1 and it runs fine. When running on battery 2 I would loose power and not run right at all.
I hope this helps."
 
Derek:
To me it looks like Yo

Derek:
To me it looks like You may have one cylinder 'out'.
Start by checking the spark-plugs and do a compression test. Too often people gets lost in the electronics and forget about the mechanical problems that might be far more frequent.
 
"Thanks for the input guys. I

"Thanks for the input guys. I think I have ran it on both batteries and not noticed a differance, but I will double check. I changed the plugs a few weeks ago and they all looked the same. I did not notice one that looked like it was not firing. Maybe I have one bad injector. I will need to do a compression test. Keep it coming please. I will check anything at this point."
 
"Hey Morten,
This is not a pr

"Hey Morten,
This is not a problem any more for me I was telling him What I did to fix mine surging problem."
 
Make sure your compression tes

Make sure your compression tester works because I got low erratic readings and changed my engine only to realize later that I had a faulty tester. Ouch.
 
"John,

I think the reason M

"John,

I think the reason Morton told you that, is that your "fix" is not a "fix". Your assumption that "battery #2 is just a starting battery" is incorrect. There is no such thing as a battery setup wherein a battery can only be used to start an engine, but not run it!. My boat for example is set up with a "start" battery and a "Dual purpose" battery. All this means is that the start battery is designed and optimized for "start" duty, i.e. start and RUN the engine.
The dual purpose battery is designed to run electronics and lights, etc and not be harmed if discharged deeply, it can also (dual purpose) be used to start and run the engine if needed. In this setup, the electronics, bilge pump, etc are wired to the second battery not to the engine or first batery. If both batteries are "start" duty batteries, then either one can be used at random (or in turn ideally) to start and run the engine.
In reality, if an engine's electrical system is operating properly ALL of the electrical energy required to run the engine is supplied by the alternator, with excess used as needed to recharge the battery (or batteries if you have a charge splitter)."
 
Thanks for the input guys. I h

Thanks for the input guys. I have checked all the cables and they all seem tight and clean. Switching batterys does not change it. I don't have a compressom gauge so I have not done that yet. The motor runs very smooth other that the flucuation so I don't think I have one cylinder out. Not sure waht else to try?
 
Power seems to be better. I ha

Power seems to be better. I had 6 adults on board this weekend and planed out fine. It takes a few seconds but seemed ok. Idle contines to surge though.
 
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