Author Topic: Compression/ running ability fl350 new to them  (Read 518 times)

Proudmitch

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Compression/ running ability fl350 new to them
« on: July 06, 2022, 09:40:20 AM »
I just picked up a 350 local to me and dreams came true lol, it will idle and start up but at high rpm it seems to struggle/not sound right I’ve gone through the carb and found nothing wrong with it and did a compression test and only got 97 without throttle wide open.
If I were to ride it down the road it’s gutless at wide open throttle but if I feather the throttle and hold it about 1/4 down it will take off and fly like a bat out of hell,
I also noticed the fuel pump puts a ton of air in the lines at high rpm but at idle no air and great flow(covered the engine in fuel lol)
I also played around with a mighty vac on the pressure port of the pump and found fuel to be able to come out of the pressure port but if I were to bypass the pump with the mighty vac there would be no air in the system
And once I’ve rode it for 10 minutes or so the engine seems hot and all fuel lines are empty and obviously begins to bog out with no fuel in the carb
My concern is with the compression and running issue at elevated rpm if I’m in store for a full overhaul and completely going through engine,
I’ve ordered a new pump and replaced the fuel lines and filter

LiveWire

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Re: Compression/ running ability fl350 new to them
« Reply #1 on: July 06, 2022, 10:15:59 AM »
97 is really low. I am surprised it idles. The check should be done WOT though.

The behavior sounds like a bad reverse switch other than the fuel line being empty. To check if the reverse switch is bad, it you can jumper the wires on the back of it to ground and the problem goes away, there's your problem. The switch is covered by a black boot on the right back of the trans.

My first thought on the air in the lines is a hole in the pump diaphragm.

Pump rebuild kit
https://www.aftershockmotorsports.com/index.php?main_page=product_info&cPath=1_43&products_id=282

Aftermarket pump
https://www.aftershockmotorsports.com/index.php?main_page=product_info&cPath=1_43&products_id=160
plate to mount that pump
https://www.aftershockmotorsports.com/index.php?main_page=product_info&cPath=1_43&products_id=255

Proudmitch

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Re: Compression/ running ability fl350 new to them
« Reply #2 on: July 06, 2022, 10:19:42 AM »
I see thank you for the reply, I know reverse works well but is there more to the story with that other than it working or not, you think I should Start looking for a rope end kit for it?
I also forgot to add the choke cable seems shoddy or cheap allowing you to wiggle the cable jacket and boot at the fitting in the carb

LiveWire

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Re: Compression/ running ability fl350 new to them
« Reply #3 on: July 06, 2022, 10:31:56 AM »
That switch detects if you are in reverse. There is a rev limiter for reverse. When the switch goes bad, the rev limiter engages all the time. If you hold WOT, it hits the rev limiter, stumbles, falls below that RPM, takes a bit to burn off the fuel then repeats. If you hold the throttle at around 1/4, you can get it to run just below the limit.

Proudmitch

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Re: Compression/ running ability fl350 new to them
« Reply #4 on: July 06, 2022, 10:55:05 AM »
That makes sense, there is a 2 post switch or sensor on the back of the tranny with no wires or anything going to it and it does seem like it acts like it’s hitting the limiter and as well I can start in gear  ;D
Thanks a ton for the input you’re helping me a lot

LiveWire

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Re: Compression/ running ability fl350 new to them
« Reply #5 on: July 06, 2022, 11:20:17 AM »
Likely someone removed both. One wire detects in neutral and the other detects NOT in reverse. The switch grounds those wires internally. So grounding the wires directly gets rid of the reverse rev limiter and allows start in gear.

The lead that was originally connected to that switch ran to the left going into a connector by the battery. Most people cut the wires and ground them. So if you find the connector over by the battery and trace the wires out, the one may have come loose.

I actually get rid of the connector and ground the wires on the other side of it. So you might have to look for that. I doubt it though because the switch is still there. I remove the connector since I want a cleaner look. I replace the switch with just a cut down bolt to plug the hole.

Proudmitch

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Re: Compression/ running ability fl350 new to them
« Reply #6 on: July 06, 2022, 12:07:55 PM »
So it being unhooked someone would have had to ground the wires out to allow it to start in gear as you said, that being said would it be a likely ground issue or bad ground issue causing the limiter to be on all the time,
Also is there wiring diagrams available for this?

LiveWire

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Re: Compression/ running ability fl350 new to them
« Reply #7 on: July 06, 2022, 12:18:45 PM »
Yeah, it would be a bad ground on just the one wire if the limiter is the problem. If the other wire was not grounded, the electric start would not work.

Page 200 is wiring diagram
https://drive.google.com/file/d/0B851Fdu_42hLdnRFSU10Y2FSb3V0NThNVVhfc094Zw/view?resourcekey=0--NDlZSGjhroFlY2K7xUB6Q


Proudmitch

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Re: Compression/ running ability fl350 new to them
« Reply #8 on: July 06, 2022, 01:13:08 PM »
Thanks a ton for the help you’re a life saver 👍