'99 Gen 1 DIY Fuel System Check and Maintenance

Kiwi Rider

I thought this may be of interest to the Gen 1 owners, specifically the '99 and '00 model owners.
Today I had some spare time after a 380km ride and thought, 'today's the day I check my fuel system compononents that I've never looked at in the 4 years I've had the ol' girl.
I've been meaning to check it over for awhile now, but today during my ride I had a lean surge at cruise speeds of between 120kmh and 140kmh. Not all the time, but more often than I was happy with. The last time I had a surging issue I found the fuel pump sleeve screen blocked with gunk, cleaned it and all back to normal.
So this time I thought I'd start at the fuel tap and condition of the fuel tank (original tank) and work my way forward to the injectors, checking everything thoroughly and sorting any issues that are there.
I want to also check the spray pattern of the injectors, using a clean white sheet of A4 paper and firing the injector at it from a couple of inches away. I do this at work with the Suzuki LT500 Quads and it works well to ascertain bad injector spray patterns, fixed a few poor running issues and the boss was impressed.
So here's some pics . . .
I know y'all like pics lol . . .

The fuel tap mesh screen is pretty dirty, what do you guys think?




Below . . this is with the screen help up in front of a flouro lamp in the garage to give you a better view of the inside of the mesh screen.

Here's the fuel sender rheostat, quite clean, but it should be, it gets fresh fuel every weekend!

The fuel tank inside has no rust at all, looks really clean!

Looks like someone's made this rubber gasket, if that's OEM, someone drank to much Saki and went to work hungover lol

Here's a few shots of my plugs, they look quite lean in my opinion, I would like to see more colour in them than that.
I disconnected my Power Commander a couple of weeks ago to see what difference there would be,I'd had a bit of rough running occasionally so I adjusted the fuelling with our Teka module at my workshop, made it 10% richer at 5-10% throttle opening, and 5% on all other throttle positions thru the scale up to 100% WOT.
We use the Teka to enhance the fuelling on Suzukis with a free flowing exhaust and Air Filter fitted.
I will recheck the plug colour after the fuel system is gone thru, and any issues fixed.



Kiwi Rider

Man great thread! thanks for taking the time to share.
Thanks Willie, my pleasure!
I will update the thread as I work thru the system . . . I found the fuel return hose (from the pump to the tank) kinked and perishing at the tank end of the hose, looks like the original hose from 1999 lol. I've replaced that.


I've also stripped the fuel tap and checked that for any crud or damage, all good.
But I will be adding a lever to the tap to be able to turn it off before disconnecting the hoses, those idiots at the fuel tap factory have cut the lever off and ground it flat! Unbelievable!!


Looks like the tap designer has a sense of humour! lmao


@Kiwi Rider

please excuse minor thread jack. the fairings I ordered come with a full tank but its naked. current tank is 10 years old and filter and pump have not been serviced in 40K (since new)

would you put a new filter & pump in the new tank or just transfer?

Also how best to store old tank? if it has the old pump it will be sealed but empty. Don't want rust or damage to pump due to no fuel or use

Kiwi Rider

@Kiwi Rider

please excuse minor thread jack. the fairings I ordered come with a full tank but its naked. current tank is 10 years old and filter and pump have not been serviced in 40K (since new)

would you put a new filter & pump in the new tank or just transfer?

Also how best to store old tank? if it has the old pump it will be sealed but empty. Don't want rust or damage to pump due to no fuel or use
Re your question about which pump to use, if it was me, I would inspect the pump in the new tank, and compare the condition of it to the original pump out of your tank, then make a judgement on which one to overhaul. New filter, o rings etc.
To store the old tank, just be sure it's totally dry inside it, remove the fuel pump and seal the hole with duct tape. Store the tank inside your hose in a dry spare room.
Strip and dry the pump, seal it in a plastic bag and store that with your tank in the spare room also.
There's a product on the market which seals the metal inside a fuel tank, some sort of epoxy spray from memory, will look into it and get back to you about it.

Kiwi Rider

For anyone wondering what I was referring to with the "Teka" module/scan tool, here's a pic.... It plugs in to the factory harness connector under the seat on most fuel injected suzukis. . .


Basic adjustments to the oem fuel map can be made, we use it occasionally for bikes with aftermarket mufflers and high flow air filters just to add a bit more fuel to the increased air flow. Works well!

Kiwi Rider

Great write up Greg.
FYI all the 99/00 fuel taps look like that. It's a sick joke from Suzuki methinks. Grinding a slot on it makes turning it with a screwdriver easy.
Funny you should say that but here's my latest post on here . . .

Today I modified the fuel tap so I can turn it off BEFORE disconnecting the fuel hose, the way it comes from the factory is permanently switched on.
I can only assume the designers were attempting to idiot-proof the fuel system, if I forget to turn on the fuel tap and and then run the engine it will run the pump dry and that ain't good for the pump motor at all.
I used a die grinder with a small half inch diameter cut-off disc to grind out the slot. My stubby screw driver fits perfectly and I lubed the o-ring in the tap to make the rotation easier, slides around nicely and not stiff to turn at all.
Pics . . . (just so ya know it did happen!)

This is the 'ON' position . .

and this is the 'OFF' position . .

I also replaced the fuel pump return hose with a piece of nice quality hose I got from work, I've been meaning to do this for months!

So that's two jobs out of the way!
More to come . . . . :thumbsup:

Kiwi Rider

Ok . . . so I've gone in for a deep dive into my fuel system, and I'm so glad I did!
Some background info . .
over the last few rides I've noticed a lean surge at cruising speeds, 110-120kmh in top gear, light throttle, low revs (3500rpm).
Now the last time I struck this issue was two years ago, June 12 2017 at 93956km
That was 27,000kms ago.
I dedicated a thread to the fuel pump rebuild,

1999 Gen 1 Fuel Pump Service. | Maintenance and Do-It-Yourself

and if you check the pics, the pump sleeve mesh screen was blocked causing the lean surge.
The clean out of the pump fixed the surge issue and the bike ran a lot better.

Well, I just stripped the pump again and lo and behold, same thing, but WORSE!!
Looks like I'm going to have to run an in-line filter that I can replace on a regular basis . . .
Check this out . . .

Below is the pressure regulator screen

A shot of the underside of the screen with the screen removed


Here's the sleeve mesh screen blockage



looking inside the sleeve where the pump sits,
that hole is where the pump nozzle fits to suck fuel through the mesh screen, look at the crud!

So, like I said, I am sooooo glad I took the time to go in and check the pump, it took me 1 hour 15 mins from start to where you see the internals of the pump, and that was taking my time at home, with coffees and a phone call included!

I will keep you posted on the clean up and reassembly phase of this operation


My 99 has some rusty tank issues that haven’t been fully addressed. I replaced the pump, filters, lines and had the injectors cleaned. I also added a metal 3/8 in/out NAPA filter in between the tank and pump. It seems to be doing its job so far and not be a restriction ( tested to top of 4th gear before common sense kicked in).

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