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2008 KQ 750AXi Fuel Filter and Pump Repair

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41K views 15 replies 6 participants last post by  Joe K  
#1 ·
So my quad has been idling rough, occasionally stalling at idle, and then last weekend going up a hill stalled and really fought me to start again....

After some reading on the interwebs, my issues seemed to be inline with a dirty fuel filter. Check this out for more info: Nyroc's ATV info website

The quad has almost 3000 miles on it, so it probably is about due for a change. I ordered a fuel pump upgrade kit for $30 from Amazon.

The stock unit was apparently very expensive, so I will only go down that road as a last ditch effort. The kit from Amazon is set to arrive today.

I pulled the quad apart Sunday. I had to remove the battery, disconnect all electronics under the seat, and remove the large back plastic. Then the fuel tank is easy to get at. Next, I disconnected the fuel line at the pump and connected a fuel pressure tester I picked up at Harbor Freight.

Fuel Pressure Tester & Fuel Injection Pump Tester

Then you have to reconnect all the electronics so the fuel pump kicks on when you turn the key. If done successfully, you will get a pressure reading. Mine read 38 psi. You should be getting 43 psi at the pump which is what the engine is tuned to run on. If you work out the maths here, that is roughly a 12% difference, which means the engine is less fuel (not sure of the relation from pressure to delivery). I have an HMF optimizer on my engine, but I am not entirely sure how that factors in as well. I'd venture to say that it adjusts the length of the injector pulse to allow more fuel to the engine, but I am not positive.

That is as far as I have got so far. I will take some picture when I work on it tonight.
 
#2 · (Edited)
Ah, too bad you didn't find the Suzuki King Quad Tech Tips on NYROC, there's a way to remove the fuel tank that doesn't need you to take all the electrics out and the plastic off. 'Gas Tank easy remove and replace'.
I once did it the hard way too, fishing all those connectors through those holes. :)

I'm interested to hear how that pump works for you.

http://nyrocatv.com/techtip.cgi?viewtopic=554
 
#6 ·
I didn't get to finish anything last night. But from the looks of it, the new pump is a good fit. I think I am going to leave the stock pump motor in for now, just replace the filter and check the pressure. I don't want to replace something that has been working.

I am going to camp this weekend and I got my buddy's Can-Am X MR 1000 as a free loaner, so I am not worried about finishing this until next week. :icon_ devil:



Here are some photos of the pump for reference:









 
#7 ·
Fuel pump and filter

Just finished this project myself, had to use the Bosch pump and Profill strainer and prefill tank insert. Finish pressure was 56psi so I had to do the
o-ring notch described in tech tips on Nyroc, pressure came down to 47.5 did the rest of the detuning with the vdi. Runs great now.
 
#8 ·
Well I finally had a chance to check the old pump with a clean filter and the new pump with the new filter.


Old Pump Old Filter: 38 psi
Old Pump New Filter: 40 psi
New CNT Pump New Filter: 67 psi

So the new pump is way overkill and I do not have the means to compensate for it. Looks like modifying the pressure regulator will be next.

Nyroc's ATV info website

As an added bonus, my new filter is rotated 180 degrees. I am thinking this whole kit may be going back. Looks like I'll be ordering the Napa filter.
 
#9 ·
The new fuel pump kit will be going back.

I ordered a new Airtex FS199 from RockAuto. Came to $14.01 shipped to my door. Can't beat that! Now I just need to get some mesh to adjust my pressure regulator.
 
#10 ·
New filter came in and I got some 5/8" stainless steel sink aerators (#40 mesh) from Sears hardware. I was able to get my fuel pressure up to 41 lbs. Not perfect, but an improvement over 38. I also checked my HMF EFI Optimizer and discovered that my fuel settings were tuned down from the recommended numbers... not entirely sure why. I turned them back to default.

Got everything put back together yesterday. So far she runs good. I am going to run some Seafoam through the engine and take her for a ride today.
 
#12 ·
First off, welcome to the Forum. Secondly, I know your searching for answers to your atv related question. But please refrain from replying to older threads as these are deemed inactive. You just replied to a thread from 2015, (5 Year Old Thread). Replying to these older threads pushes the newer ones down the queue. And in most instances, you will not receive a reply from the OP as he or she is no longer active within the Forum. We actually encourage you to create your own threads for any atv related questions you may have. All this is clearly stated within the Forum rules which you are required to read upon signing up.



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#14 ·