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post #1 of 12 (permalink) Old 08-19-2019, 11:26 PM Thread Starter
John from Washington
 
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Summit 670 fuel pump questions

1997 Summit 670, with 130 compression on both cylinders. Replaced fuel pump on my Summit 670 last spring. Got a $29 deal off Amazon (hold that thought). After initial installation, it would start with 2 pulls. All was good!


Tried to start it last week (2 pulls). It runs for a seconds then dies. I thought it was "cold" and kept repeating the process, after the 8th time, I decided to investigate. The fuel lines to the carbs were dry!!. I used to have a "air bubble" at the top arc of my fuel line, I noticed the last 8 or 9 inches of my fuel line (from fuel bowl back to pump) is dry. Did the fuel pump die?


Questions:

1. Is it normal for $29 fuel pump to last one season? I use NON ETHANOL with Sea Foam

2. Any one know a good fuel pump brand to buy ?

Many thanks in advance.
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post #2 of 12 (permalink) Old 08-20-2019, 09:29 AM
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First thing I would do is pull the fuel lines from the carbs and see if any fuel comes out when you pull the rope. If the inlet needle and seats are stuck shut (likely) not much fuel can be pumped into the lines.



Then check the hose inside the tank. If it has collapsed or fallen off and the fuel level is lower than the outlet of the tank, you won't get any fuel.


A third problem could be the hard "impulse" line that goes from the crankcase to the fuel pump. If it has cracks or leaks, the pressure/vacuum created by the movement of the piston in the crankcase that drives the fuel pump diaphragm won't make it to the pump.


You may want to disassemble the fuel pump to see if the small one-way valves inside the pump are stuck, too.



After-market parts are sometimes of less quality than OEM, so that could be part of the problem. You can buy kits for the fuel pump that contain all the parts needed a lot cheaper than having to get another fuel pump.



Good luck!

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post #3 of 12 (permalink) Old 08-20-2019, 11:29 AM Thread Starter
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Thank you BC Dan.

Disconnecting line from fuel bowls and checking if fuel moves by pulling the rope is a good way to check for the stuck needles. Wow, I never thought of that!
I'll double check the impulse line, but I replaced it when I replaced the fuel pump.
Lastly, I'll go ahead and replace the tank pick up line and tank grommet. On my 2002 Summit, the pick-up line was thin/perforated and I replaced it when I replaced its fuel pump. I'll bet it is not great on this '97



Quick easy questions
1. I still have the original bombardier fuel pump and ordered a rebuild kit. I also ordered the little tool to install the one-way valves. The gaskets and membranes seem like a no-brainer. Any special technique to install the one way valves?

2. Can a rebuild kit be installed on a OEM fuel pump?
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post #4 of 12 (permalink) Old 08-21-2019, 12:17 AM
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No idea on the special tool, on Arctic Cat and Polaris fuel pumps, I just gently push them in. A kit should work fine on an OEM pump.


If the fuel pump does not have indexing marks, it's a great idea to scribe a line across the parts of the pump so you can assemble the pump back the same way it came apart. Don't ask me how I know this

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post #5 of 12 (permalink) Old 09-08-2019, 11:39 PM Thread Starter
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I would like to report back in the hopes our dialog will help others. I pulled the fuel line and then pulled the rope....gas flowed, so I replaced the float valves. Starts and runs.


Thank you for the guidance.
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post #6 of 12 (permalink) Old 09-09-2019, 10:55 PM
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Awesome! Snow is coming, good to get it running!

2017 SKS 800, 2007 Dragon RMK 700 155", 2008 RMK 600 155", 95 Prowler 550 2-up, Really OLD AC Cheetah

http://www.avalanche.org/accidents.php
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post #7 of 12 (permalink) Old 09-10-2019, 07:41 PM
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If this is the first time starting it after sitting for a while, fuel pumps don't work very well when dry. I usually pressurize the fuel tank and watch the fuel flow into the carbs.

Once fuel is in the system, let it sit for a minute or two and then try starting it up.

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post #8 of 12 (permalink) Old 09-13-2019, 08:32 AM
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I usually will grab the gas tank vent line and blow into it, don't use a compressor it can blow lines off!
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post #9 of 12 (permalink) Old 09-14-2019, 10:34 AM Thread Starter
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Good tips. I 'd like to emphasize for others that pulling the carbs and changing the float valves was very straight forward. There are many very good Mikuni carb rebuild videos to reference.

At first, it seemed like a daunting task. The last time I took apart a carburetor was in high school with my teacher near by. That said, the disassembly process was identical to the YouTube videos. I tested the start up (and run) after a 24 hours to make sure it was holding together. I held off for 2-days and then again for another 3 days. Started and ran every time. I was able to "give it more gas" without dying.

I did not want to introduce too many variables into the repair, so I used carb cleaner in the jets. I might a attempt a full rebuild at the end of the season.

Remember -- Use non-ethanol gasoline in these machines.
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post #10 of 12 (permalink) Old 09-15-2019, 08:07 AM
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Rebuilding is perhaps a strong word, cleaning is more correct.
When you replaced the inlet valve (needle and seat) did you set the float 'Level'?
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post #11 of 12 (permalink) Old 09-15-2019, 03:40 PM Thread Starter
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I didn't check the float level. I installed the new parts and out the carbs back on started from bone dry in 4-5 pulls. After that 1 pull starts.

I'll see how everything is working when I "visit" the machines next month. Any symptoms I need to know of incorrect float level?

thanks again
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post #12 of 12 (permalink) Old 09-16-2019, 06:46 AM
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May starve at high rpm or leak
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