Lets talk accelerator pump adj
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=4712
Printed Date: April-29-2024 at 12:01pm
Topic: Lets talk accelerator pump adj
Posted By: 77stang
Subject: Lets talk accelerator pump adj
Date Posted: September-07-2006 at 12:47pm
I run my holley a little leaner than before and i'm getting the best top end that i every have. Only problem is that i get a hestitation on acceleration. Now lets ignore timing issues - i'm very confident that i'm well dialed in after adding ie.
The first thing holley trouble shooting suggest is adjustment to the accelerator pump (diapham pumps very well when held down at wot as the manual suggest it should) and that adjustments are made by inserting .015" feeler gauge between the adjustment screw and the pump arm. However when i try to adjust the screw the nut on the bottom of the screw turns also. it doesnt appear as though the spring is adusting. ADDITIONALLY, I CANT GET THE FEELER IN BETWEEN THE SPRING AND THE ARM)
First question is should that nut on bottom of screw turn with turns to the adjusting screw
And second - Does this sound as though my hestation is due to too much pump action as opposed to too little pump action which seems more logical to me.
All comments from members who have performed theis adjustment are appreciated.
Thanks
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http://correctcraftfan.com/diaries/details.asp?ID=1360&yrstart=1971&yrend=1975 - '77 Mustang 17
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Replies:
Posted By: 79nautique
Date Posted: September-07-2006 at 1:02pm
the first thing to look at is if it is squirting gas for the whole stroke of the throtle. disconnect the cable and manually move the throttle on the carb while holding the top butterfly open and looking for gas to squirt out of both front barrels for the full stroke of the throttle if there is a slight pause before it squirts gas while moving the throttle then it needs to come on sooner and needs adjusted. If it squirts gas as soon as the throttle is moved then you need to look at the timing and/or richen up the idle curcuit so it doesn't stumple coming off of the idle curcuit in the carb.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: 77stang
Date Posted: September-07-2006 at 1:17pm
thanks 79, i'll take a look at that and get back - just have to wait till i get someone here to smash it down to wot
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http://correctcraftfan.com/diaries/details.asp?ID=1360&yrstart=1971&yrend=1975 - '77 Mustang 17
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Posted By: GottaSki
Date Posted: September-07-2006 at 1:47pm
You need two wrenches.
Often the step that gets lost in the translation is to do this adjustment at WOT. Many people dial in their hesitation to remarkable precision.
Done the correct way there is no slop in the linkage at idle, and the .015 clearance is so it doesn't mechanically bind at WOT.
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole
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Posted By: 77stang
Date Posted: September-07-2006 at 2:00pm
those comments are why i'd pay to post on this site - much appreciated; both of you
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http://correctcraftfan.com/diaries/details.asp?ID=1360&yrstart=1971&yrend=1975 - '77 Mustang 17
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Posted By: Hollywood
Date Posted: September-07-2006 at 4:39pm
You could always donate if you haven't already.
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Posted By: 77stang
Date Posted: September-07-2006 at 4:44pm
OK,
The only way i get fuel squarting is when i depress the arm very quickly then - i get a full blast the whole depression. If i press the the arm slowly it doesnt appear i'm getting any fuel at all. Not really what i expected to find.
Comments
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http://correctcraftfan.com/diaries/details.asp?ID=1360&yrstart=1971&yrend=1975 - '77 Mustang 17
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Posted By: GottaSki
Date Posted: September-07-2006 at 7:01pm
There is a check ball under the diaphram that might not be sealing well, allowing the fuel to drain back and the circuit fills with air; air must be dosplaced before you see fuel.
Some units may have additional check ball under the nozzle, I'm not certain.
On older carbs there are also o-rings on the little accel pump transfer tube that may be suspect, also. That is between the metering black and carb body.
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole
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Posted By: nuttyskier2002
Date Posted: September-07-2006 at 9:44pm
77 your accelerator pump plunger may need to be replaced. It may not be sealing completely. You should get a shot of fuel from the pump regardless of how slow or fast you pump the accelerator. Also, after running your boat at WOT did you shut it down and pull your plugs to look for indications of running too lean. At WOT an engine will scream when running on the lean side just before burning a hole in a piston. I'd check for this if I were you.
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95 Malibu Echelon w/Mercruiser 350 Magnum Skier
Former boats:
88 Ski Centurion Tru Trac II
59 Chris Craft Capri (woody)
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Posted By: 79nautique
Date Posted: September-07-2006 at 10:58pm
man..... following instructions is hard, more beer needed I guess.. disconnect and move throttle.....nobody said move the shifter,
If it doesn't work right with out it running then having it running isn't going to fix it or make a difference.
The accelarator pump is mechanical doesn't require vaccum to test stroke or adjustment.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: nuttyskier2002
Date Posted: September-08-2006 at 1:42am
Hey 79, calm down a little man. In my above statement, I was refering to 77's original post where he said "a little leaner than before and i'm getting the best top end that i every have". I was just concerned that maybe he might be running his carb a little too lean which will definitely harm his engine. When you get too lean, the combustion temp goes too high and you start burning pistons. Part of the fuels job in the combustion process is that when it turns to vapor it absorbs engine heat which aids in cooling the engine. When you get too lean on the air/fuel mixture, that cooling effect is taken away. I learned this by taking the same cla$$es to get my ASE certs as you did.
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95 Malibu Echelon w/Mercruiser 350 Magnum Skier
Former boats:
88 Ski Centurion Tru Trac II
59 Chris Craft Capri (woody)
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Posted By: 79nautique
Date Posted: September-08-2006 at 8:37am
I'm calm checking the accel pump is a one man job done with the engine off and the shifter doesn't have to be move to do it, you just have to disconnect it at the carb so that you can run the throttle while looking down the carb, pretty basic stuff, so if your not getting a steady stream for the full stroke moving it slowly then it's not adjusted right or the diaphram is bad end of story, and you never want to run a holley carb on the lean side to start with or any carb for that matter, on a holley it max vaccum, a q-jet or edlebrock are a little easier if you know what your doing.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: GottaSki
Date Posted: September-08-2006 at 8:57am
77, you mean your actually changing jets or just futzin with air screws?
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole
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Posted By: 77stang
Date Posted: September-08-2006 at 9:55am
GottaSki -
Gosh No im not messing with the jets - just getting the adjustment on the spring to spec. We'll see if that helps, i'm hoping it does. not really interested in opening this thing up - i've always been apprehensive to get inside a carb, but i'll do it if i have to. Your other diagnosis suggestions were right in line with the manual
nuttyskier2002 -
before i leaned this thing out my plugs showed signs of being way to rich - i could actually smell the fuel. after leaning it out i pulled the plugs the first couple of times to see how they looked and they looked good. Sincerely appreciate the warning and what your stressing on this.
79 -
i didnt want to disconnect the throttle if i didnt have to, too many parts that may fall into my turkey and water (beer doenst get me where im going quick enough - especially in OK with a 3.2 limit). Plus it gives me a chance to show the kid what i'm doing and take turns with him sticking our noses into the butterfly. I wait on him to do lot on this old boat that are one man jobs just so i can impress him with my ignorance.
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http://correctcraftfan.com/diaries/details.asp?ID=1360&yrstart=1971&yrend=1975 - '77 Mustang 17
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Posted By: GottaSki
Date Posted: September-08-2006 at 5:22pm
Good to hear on the accuracy;
Ok then, you can twist the air screws all day, it won't frag the engine, nor change your top speed; it must be something else responsible for the extra speed.
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole
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Posted By: 77stang
Date Posted: September-08-2006 at 7:52pm
keep in mind that i installed the ie, retimed the motor and leaned it out all in the same weekend - so i dont know which of those would have the greatest impact on top end just that its running very well on the topend and hesitating out of the hole.
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http://correctcraftfan.com/diaries/details.asp?ID=1360&yrstart=1971&yrend=1975 - '77 Mustang 17
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Posted By: nuttyskier2002
Date Posted: September-09-2006 at 5:58am
Of the three things you mentioned above, timing would have the biggest influence on your top speed. Glad to hear you are not leaning the jets. Never do this on a boat! You would be asking for trouble. BTW late ignition timing will give some of the same symptoms as running rich.
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95 Malibu Echelon w/Mercruiser 350 Magnum Skier
Former boats:
88 Ski Centurion Tru Trac II
59 Chris Craft Capri (woody)
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Posted By: 79nautique
Date Posted: September-09-2006 at 9:28pm
the cable is easy to disconnect and nothing to lose. The end is spring loaded and you slide the sleeve back and then it will come right off of the throttle lever on the carb.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: stang72
Date Posted: September-10-2006 at 12:15am
Or...if yours does not connect that way...remove one cotter pin...and disconnect!
so...it will take you either 5 seconds...or 30 seconds to disconnect and check it that way!
Doing that check...will tell you what you need to know in regards to the acel pump....it's simple and the Turkey and H2O is safe!
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stang
Face plants are not that funny when it's you face!
http://www.correctcraftfan.com/diaries/images/3720/photo1.jpg" rel="nofollow - The Super Air
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