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Primer pump issue ?

19K views 29 replies 8 participants last post by  _Wilson_ 
#1 · (Edited)
Issue goes like this, last week it was deep cold here, 6, didn't want to fire off.... (note) I've never touched the primer till now and after i did, (stock 99 fourtrax 300 4wd) she finally fires so i went on my way, i noticed a new issue, after i let up on the throttle she drops in rpm for a few seconds, then returns to normal rpm ( 1400 ) + or - 100, she acts like there's a moment of rich gas dumped into the chamber, my question is, can the primer cause this issue, i wanted to run this by you fellows before i purchase a new oem and has plenty of low and high rpm performance no other issues besides the above, shop manual is no help,

GENUINE-HONDA-CARBURETOR-PRIMER-PUMP-KIT-16048-HN7-003

Checked out good:
1 plenty of clean fuel
2 spark plug is firing as it should
3 fuel filter/screen spotless
4 air filter clean and foamed
5 petcock on, lol
6 gas is getting to the carb perfectly
7 vent in gas cap working fine
 
#9 ·
Okay ....... She ran fine today , no drop in rpm, question........ If the vent line is pluged..... When i drain the carb bowl, will a pluged vent be a tell tell sign ? Or will it drain never the less ( slowly ) cause mine drained faster the further out i un screwed the bowl drain screw
 
#4 ·
Thanks guys! Could be moisture, but ...... I have always kept the tank topped off all the way up to the neck vent hole, right under the gas cap, and i never use reserve, it was warm today, still does the same thing, cold or hot, my bad for not adding that fact, no leeks at the primer, could the cause be some trash that was some how or another broke loose when i primed her ? I'm still blank on this issue, ..... Cause she's always ran like a sewing machine, I'll check the plug TM for carbon build up, and check the exhaust for black fluffy carbon, she seems just on the verge of cutting out , only thing i can think of at the moment is taking off the air filter and covering the intake with my hand and turning the engine over to dislodge what ever is causing this, i can't think of anything else i should check, I'll update soon, thanks again guys, very helpful !
 
#5 ·
I can't see the primer having an effect on the way it runs , unless there is trash in the carb and you swooshed it around by priming ------------ I know I would not pay $50 for a OEM primer pump from Partzilla , the ones off e-bay for $10 have worked fine for me for a long time , Chinese parts are usually junk but this is one I do , the local dealer of ATV/UTV's Friendly Power Sports in Slidell told me $90 for one primer for my 300 , I didn't get it , they are so much higher than any of the other dealers in the area , double on a lot of things I price from them as compared to Picayune or Covington
 
#6 ·
Yeah fish flushed around trash is what I'm thinking, so i went back out and drained the carb, the gas looks perfectly clean, NO sign of trash, filled it back up primed it again, primer did build a bit of back pressure and sprang bck out like normal, no leeks, so i drained it again, same , perfectly clean gas ......... I collected a sample and I'll let the fine trash (if any) settle for a while and see.....
 
#8 ·
Thanks fish, and this morning the light revealed trash in the sample......s I'll be pulling the primer pump for inspection.....
 

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#10 ·
primer bulb

i capped off my primer bulb on the 2000es. i didnt cap off the feed. if sediment can get there any where, it will. i forget the rule, but, if it can happen, it will happen. maybe not for you, but for someone. i didnt know primer button was so cheap when i capped mine. for that price, i will replace what i got. seemed like it was over $50., back then.:big-grin //Ed
 
#12 ·
Something else is happening..... Engine denotation (knock) JUST. (Never did this before) On start up, my new question is, if it just happens on startup, should this be a concern ? IE ( engine damage ? ) And what could be the cause of this new issue, added it only happens when the engine is warm...... Could this be a the NGK iridium spark plug i swopped to ? I run only 87 octane gas, treated with red stabil .
 
#13 · (Edited)
If it spark knocks on startup (assuming this is not a mechanical problem) its generally a temporary problem due to an aged fuel/lost octane issue. If it is an ethanol-laced fuel it might have been rotten straight from the pump.

Other causes for pinging are excessive carbon buildup in the chamber and/or excessive motor oil getting into the chamber. Think worn & leaky valve seals, worn out piston/rings, broken ring, etc. Motor oil in the chamber used to be the number one cause... but nowadays its generally a rotten fuel issue involving the ethanol scam.

EDIT:
Forgot to mention... Stabil treatment is only effective if using non-ethanol fuel. Minimum octane rating of fuel should be 89 (and fresh) before adding any treatment additives. Treating ethanol laced fuels are like putting lipstick on a pig. Ya can't turn garbage into gold... Let us know if fresh fuel fixes it...?

Check around the intake for a cracking or leaking carb boot too.
 
#14 ·
real fuel v/s ethanol fuel

retro; if you are in a place where you can get 87% non ethanol fuel, would you have to add octane to it? also, i thought some of those fuel stabilizers were created for ethanol fuel. perhaps i need an ED-ucation. //Ed
 
#15 ·
Its cheaper (and more effective, since many/most octane boosters are a misunderstood scam) to buy a mid grade or higher fuel in the first place.

There is a Stabil product that is formulated for ethanol laced gas (its not very effective) and one that is intended for non-ethanol gas. I use the original red label stuff sometimes myself. My point about using a stabilizer for 89 octane minimum fuel is that with 87 grade there is nothing there to preserve (poorest, cheapest grade available, with winter grade gas being the worst possible fuel) in the first place, so its a waste of your additive. If you buy low grade fuel it should be consumed immediately with fingers crossed.

And if you buy ethanol laced fuel of any grade there ain't no fixing it no matter what... or any hope for effective short term storage of it... Ethanol contains significant percentages of water and other organic impurities along with oxygen, so it is bio-degrading rapidly from the moment it is created and will continue to rapidly rot until all oxygen-driven chemical reactions cease.

I'd simply change the fuel in the tank to a premium (non-ethanol) grade during the winter months if you are having problems. Winter grade fuels are not your friend...
 
#16 ·
I had some trouble getting non-ethanol fuel last Friday , with all the ice on the roads during the week the deliveries were backed up and the station I usually go to was out , I had to drive 10 miles out of my way to another station that had it , but it was worth it , I usually buy 20 gallons at a time , add Red Stabil to the storage cans and a shot of Sea Foam to every tank fill

ironic this thread is about fuel primers , Sunday I rode my wife's bike when mine had a problem , I jumped on it and didn't check the fuel , so after about an hour I ran out and had to switch to reserve , I tried to press the primer valve and it is stuck solid , I was just going to change the primer , but think I should pull the carb off and see whats going on inside , have never had that happen before
 
#17 ·
Thanks for the info guys, IF...... I have time I'll be testing between spark plugs and I'll be pulling off the primer, can the knock (ping) on startup cause any engine damage ? Or..... Is this the nature of honda engines ? Fish...... Same aggravation here ...... I should have never touched that dang primer, little Johnny had always said as they age they can cause issues. EI leeking , sticking, and (yes) as fish stated swooshing up trash, i don't think this is an oil issue, cause I've never had to add any at all, again it might be my misstake adding a bit because now she's a tad over the upper mark, so I'll be pulling some back out , that part I'm happy about i didn't account for the high tire pressure in the front over 10psi and only 2 psi in the back .
 
#18 ·
...can the knock (ping) on startup cause any engine damage ? Or..... Is this the nature of honda engines ?
Yes, it certainly can (and will) damage the motor. No, its not the nature of a Honda motor. Since this might be a winter grade fuel problem, you'll probably need to buy a premium grade of fuel to solve this problem... at least until the refineries switch back to supplying summer grade fuel again. I'm interested in what you discover...
 
#19 ·
Thanks! Retro, i sure will post my findings, hope it warms up some so i can get this issue adjusted.
 
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#21 ·
I thinking a little differently on the knock. A true pre-detonation knock requires heat: something not present at a cold morning start. However what is present is a lack of lubrication. This can cause a mechanical knock. Perhaps you can change your oil to 0-20 synthetic. Maybe a 5-20? I think this may solve your problem knock and if so will prevent an oil starvation scoring on your cam, rockers and maybe your piston.
 
#22 ·
Thanks MC is i should have mentioned it was wrapped up a rag and stuffed in the trunk as a spare plug, it was wet, when. 1st took it out, and the knock was only on hot start ups, odd thing, not every single time, at the moment has gn4 10w-40 , 87 grade gas is what i have in the tank, it has never pinged on cold of warm starts, only on hot fire ups, I'm thinking a better grade of gas, I've never ran the tank empty so....... Im also thinking maybe too much red stabil, a dif weight oil is on my mind.....i had a freekn pic of it (then) but heck if i know what i did with it........
 
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#23 ·
Start up is a very unique situation. If you think about it , the engine is running ( for a very short time) at an RPM not recommended for your engine. As a result unusual stresses are imposed on your engine. This can cause a mechanical knock on worn parts and a true pre ignition knock. A worn engine can easily run too hot because of the inefficient heat transfer thru the worn rings and combustion blowby. Also carbon in the combustion chamber can increase the compression ratio and cause hot spots. You could run a higher octane fuel, reduce the heat range on your spark plug and/or retard your ignition timing a degree or two......that is if it runs good otherwise.
 
#24 ·
Thanks MC ^^^^^Just what i was thinking i can't see this motor being even close to being worn out, its never been cracked open n uses no oil, no blowby she starts with no choke at all, and it has to be really cold out ie 10 or below, a better grade of gas and a colder plug is what i plan 1st if i can just get some warmer weather and dang wrench time , little Johnny checked this thing from top to bottom and it only on it second set of tires, still had 3/4 tread on the oem h-track tires, the more i think about this , I'm thinking too much stabil and that plug, I'll post updates soon as i can change that plug and freshen up the gas, it's got to be that gas.
 
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#27 ·
Update, i pulled all the gas out even tipped her over on the left hand side, drained out as much as i could, the tank is completely rust (i already knew) and dirt free, the screen was spotless, air filter clean n oiled, re filled with fresh gas 87 , 7ea-9 plug , engine startup ping GONE! She NOW sounds like a sewing machine (perfect!)

I never changed one single thing except the over treated gas......Mc ..... I still plan to check the valve clearance ......she even fires up better, i reckon even red/green stabil has draw backs.....thx for the help n advise,

Fact..... Ethanol (corn) gas is crap!
 
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#29 ·
i had to leave for a minute, an forgot where i was

glad to see ya got er going there wilson. been following this thread. i got three gas stations round here that sell non-ethanol. 1st, 12 miles away, the others 20, or so. i dont remember the octane rating, at the clostest, an mean to find out. the gas has a different smell than B/S gas, an the atv engine, and all 2 cycle engines, weed wackers an such, run better, on this gas. its like having your guitar tuned, and now you know why it sounds bad. the station attendant told me that new vehicle motors, cant run on the good gas, because they are designed, to run with B/S gas. run like crap in other words.
that non- ethanol gets better readings at the smog checking place, your car dont, and runs worst. when you had to do that vehicle test in the past, your car would be running perfect, yet, would not pass . an so adding rubbing alcohol to the tank, it would pass with flying colour's, but runn like crap.

everything is fixed, by unknown forces, that have nothing to do with the equation. am i philosophical? good thing i cant spell, an my dictionary is from england stead of KY, or i could, Ramble On. i will re-edit tomorrow or so.
 
#30 ·
I showed this pic to a few members , each made comments about how much darker ( i agree) this gas is, YES. It's darker then the fresh i swoped to, I'm going to let this gas settle for a while just to see what happens, note.... It's been treated with red stabil (according to the instructions) per 5 gallons, the station pump has a 10% ethanol stamp on it....I'll be looking for another place to get fuel from now on....
 

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