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At wits end with carb

Discussion in 'Suzuki Carry' started by dalez0r, Jan 27, 2020.

  1. dalez0r

    dalez0r Member

    Current problem: van wont start, hardly fires, smells rich, pumping throttle makes it worse, holding choke wide open only helps slightly but still wont start.

    Brief history: Bought bc no compression and carb was gushing fuel. Messed with float, fixed gushing, adjusted valves fixed compression. Ran for a while but never right, and has gotten worse to present state. Have completely disassembled and cleaned carb, new rubber in it, new needle (old was bent!!), new spring, lots of new parts, STILL no joy. Pretty sure it's too rich to run, starting fluid makes problem worse, and I've had to run with the 'fine AFR adjust' screw almost all the way out for it to run at all... till now, nothing. And yes, I've been through the carb tuning thread, and know how all the adjustment screws work.

    Possibly related: the fuel tank seems to pressurize quite a bit when temps rise (normal action w/ charcoal can?) and aftermarket low PSI fuel pump (which weeps fuel when temp rises)

    I dont even know what the heck to do with it now.
  2. installater

    installater Member

    No mechanic here, from all the posts that I have read most seem
    to bring up vacuum lines are all yours connected right and in good shape
    Who knows
  3. Jigs-n-fixtures

    Jigs-n-fixtures Active Member

    With the tank pressurizing the carbon evap tank could be clogged. Not allowing proper venting of the system.
  4. dalez0r

    dalez0r Member

    Jigs you're probably right there, so yesterday I cracked the fuel cap to stop that temporarily, let it sit a few hours, then tried to start it. No fire.

    Checked compression: 25-125-25 - crap. less than 1500 miles ago it was 125-125-125. Fuel washed cylinders? Should the one good cylinder start the engine or is my problem elsewhere?

    Checked timing: 5* BTDC at 500rpm (cranking speed) - got spark on all 3.

    Starting fluid makes it's half*** firing stop completely.


    Just in case the flooding hadnt cleared enough to start it, I popped out the plugs last night and am gonna let it air out till tomorrow afternoon. I'm also gonna squirt a few CC's of oil into the bores and spin it plugs-out first, hopefully get my compression back...
    Last edited: Jan 28, 2020
  5. Jigs-n-fixtures

    Jigs-n-fixtures Active Member

    Timing should be pretty close to whatever you spec is, if you can crank it at 500-rpm. Your tent to set it before the centrifugal and vacuum advance begins, so lower doesn’t hurt if you can get a consistent spark.

    You could probably spin it with all the plugs out, and set the timing and be really close to the 900-rpm or so you’re supposed to set it at. My Hijet is 7-degrees at 900-rpm, with both vacuum hoses plugged.

    Just a thought, but you might be able to clamp the fuel hose, so no fuel gets to teh carb, and try starting it with the starter fluid. If that kicks it off you’re definitely fighting a rich mixture issue.

    I just rebuilt the carb on my Hijet, and had to pull it on and off the truck 4 times, before I finally got the float right, and it wasn’t running too rich or too lean. And, stupid me, I forgot to write down what the level was the last time I reset it. Had to park it outside, and start it when it was chilled down to about 10-f before I could set the high idle speed. No spec, just decided to set it at 1300, which is about 350-rpm higher than the idle setting. It would regally be helpful to have some initial settings for the carbs. But, apparently the Japanese have to send them back to the manufacturer for service, and they aren’t published.
  6. SDK1968

    SDK1968 Member

    ^^^ great advice as always..... im gonna try unhooking the fuel line tomorrow nite & see if it will fire up on ether then. cause man it was running just fine & now it sounds exactly like the OP's starting procedure up there... & thats with the new carb set up!

    kinda related: what type of fuel pressure does that pump in the tank actually put against the float?
    Jigs-n-fixtures likes this.
  7. dalez0r

    dalez0r Member

    Mine is external pump, and not even the factory one. And the label fell off, so no telling what psi. I have a 2.5-4psi pump arriving tomorrow.
  8. Jigs-n-fixtures

    Jigs-n-fixtures Active Member

    I installed a 5-psi pump on the Hijet, with a regulator immediately after it. I would/should have put it closer to the carb. (You typically should keep the pressure high until as close to the carb inlet as you can.) But, since I have a dump/scissors lift bed, it is really easy to get to the top of the fuel tank, and a pain in the tuches to get to the top of the engine, I installed it right after the fuel pump, on top of the tank.

    Right now I have it set at 2-psi. No idea what the stock spec is. But the 2-psi got the engine leaned out just a bit, which it needed.
  9. fmartin_gila

    fmartin_gila Active Member

    Don't really have any specs to give, but just from general experience many years ago I found that these type carbs do not like pressure higher than about 2.5 #. A good adjustable low pressure regulator may be a good addition between the pump & carb. On the Rotax & Cuyuna Engines we used in Ultralight aircraft, we used a "thumper" type pump which was powered by the rise & fall of pressure in the crankcase lower end which charges the upper end thru ports in the cylinder walls(2 cycle engines).

    Limestone likes this.
  10. dalez0r

    dalez0r Member

    any good leads on a 2.5# inline regulator?

    Also... im thinking my valves somehow fell out of adjustment again, or it's eating the valve seats. I tried oiling the cylinders in case they were fuel washed, and I'm still at 25-125-25PSI compression. I had 125-125-125 less than 2000 miles ago after I adjusted the intake valves. wth.
  11. matt167

    matt167 Active Member

    Use the pump for a 1983 Honda Civic. You'll have to change the leads but it will mount in stock location and it's a 'thumper' pump like the original.
  12. SDK1968

    SDK1968 Member

    think you guys are on to something... i had a left over adjustable regulator & stuck it on there tonite. set it at 2psi.

    turned the key on, checked for leaks & cranked her............................... FIRED RIGHT UP!!

    now ive got no clue if this is a perma fix or if it was my lucky day. my new throttle cable will be here tomorrow then i'll see if it works again & if it lasts!

    gonna go ad this info to my carb thread.
  13. Jigs-n-fixtures

    Jigs-n-fixtures Active Member

    Most small carbs want to see about 2 to 3-psi at the inlet. Any more they and they will let fuel past the needle, and flood the bowl, resulting in a rich mixture.

    So, Hopefully your golden. I use the variable pressure regulator on mine to fine tune the air fuel mixture.

    I’m running this one: Mr. Gasket 9710 Fuel Regulator https://www.amazon.com/dp/B000BWAPQ6/ref=cm_sw_r_cp_tai_FbKmEbABWT8VZ
  14. milmor88

    milmor88 Member

    Hey i had same to similar issues the valves needed replaced...in the process of doing that today. They come 1mm too long and you lap them then grind the top of the valve stem to get the clearance right. Major PITA/ I have read there was an issue with the hard surfacing on some of the valves. Changing thickness of the shims will temp fix it but as the new metal is exposed it erodes away fast and fast...this was on a da63t
    Last edited: Feb 20, 2020
  15. SDK1968

    SDK1968 Member

    dont want to thread jack the OP..... but the regulator did the job.

    at 2.75lbs its keeping up with any demand & its not flooding out!
  16. dalez0r

    dalez0r Member

    Turns out my carb, after I replaced the needle and diaphragm, is mostly fine. Still need to tweak it a bit, but mostly there.

    The real problem is after only 2k miles my intake valves werent closing. Tightened **LOOSENED** them back up, have compression again, fired right up.

    Will update in another 2k miles =\
    Last edited: Feb 12, 2020
    Limestone likes this.
  17. milmor88

    milmor88 Member

    Are you grinding the shims on top the valves to make more room between cam and shims?
  18. dalez0r

    dalez0r Member

    Shims?? No, I'm loosening the adjustment nut and turning the screw and retightening the nut, re-measuring the clearance at each step.
  19. milmor88

    milmor88 Member

    I guess I'm working on a 2006 da63t it might be different with the k6a engine....wish it was that easy on mine!

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