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cutwater
04-15-2010, 02:51 PM
I have a problem with the Minx... 350ci / OMC dressing / Quadrajet carb

While cold, after priming the fuel supply (pumping the throttle a few times), I can get the engine to start only with the throttle at idle. It will run for about 30 seconds at idle then shut off. If I do this enough times to warm the engine up, it will pretty much idle without issue after that.

Once warm, I can gently increase throttle to about 1000 RPMs. Applying any more throttle than that, and the engine cuts off.

However, if I pump the throttle several times before starting, then set the throttle forward, it WILL rev to 4000+ RPMs for a second or two before shutting off. This makes me think it's more of a fuel delivery issue.

I installed a brand new fuel/water separator filled with fresh gas, and checked that the fuel supply IS on. Problem still there. I have a few ideas as to what it might be, but would like to hear your thoughts first...

fogducker III
04-15-2010, 03:16 PM
fuel pump? partially blocked in-line filter?

RedDog
04-15-2010, 03:23 PM
I'd say the root of the problem is from not running in the 2009 season :outtahere::outtahere:

Cuda
04-15-2010, 03:27 PM
I'd check the fuel pump pressure.

DonziJon
04-15-2010, 03:27 PM
Shift cable adjustment at the carburetter which engages the cutoff switch. Actually it's mounted on the right side exhaust riser. A simple adjustment. Do it with the boat in the water.

mrfixxall
04-15-2010, 04:04 PM
I have a problem with the Minx... 350ci / OMC dressing / Quadrajet carb

While cold, after priming the fuel supply (pumping the throttle a few times), I can get the engine to start only with the throttle at idle. It will run for about 30 seconds at idle then shut off. If I do this enough times to warm the engine up, it will pretty much idle without issue after that.

Once warm, I can gently increase throttle to about 1000 RPMs. Applying any more throttle than that, and the engine cuts off.

However, if I pump the throttle several times before starting, then set the throttle forward, it WILL rev to 4000+ RPMs for a second or two before shutting off. This makes me think it's more of a fuel delivery issue.

I installed a brand new fuel/water separator filled with fresh gas, and checked that the fuel supply IS on. Problem still there. I have a few ideas as to what it might be, but would like to hear your thoughts first...

Theirs a bronze rock filter in the carb @ the fuel inlet,,remove and clean,reinstall.. pm me in the am and tell me how good i am :)..

No pm then check all the fuel line connections,,you may be loosing the fuel pump prime which takes forever to get fuel from the tank to the fuel pump..

or like stated you fuel pump may be going out..

joseph m. hahnl
04-15-2010, 04:49 PM
I have a problem with the Minx... 350ci / OMC dressing / Quadrajet carb

While cold, after priming the fuel supply (pumping the throttle a few times), I can get the engine to start only with the throttle at idle. It will run for about 30 seconds at idle then shut off. If I do this enough times to warm the engine up, it will pretty much idle without issue after that.

Once warm, I can gently increase throttle to about 1000 RPMs. Applying any more throttle than that, and the engine cuts off.

However, if I pump the throttle several times before starting, then set the throttle forward, it WILL rev to 4000+ RPMs for a second or two before shutting off. This makes me think it's more of a fuel delivery issue.

I installed a brand new fuel/water separator filled with fresh gas, and checked that the fuel supply IS on. Problem still there. I have a few ideas as to what it might be, but would like to hear your thoughts first...
Dirty Jets or water in the float bowl. ETHANOL:doh:
Sounds like it is running off the accelerator pump charge.


WILL rev to 4000+ RPMs...

Don't do that:boggled:

cutwater
04-15-2010, 09:16 PM
I'd say the root of the problem is from not running in the 2009 season :outtahere::outtahere:

Cheap shot :) lol. I have made it a priority this year to get the boat ready before July!

I don't think I have an inline filter. I will check the rock filter at the carb.


Dirty Jets or water in the float bowl. ETHANOL:doh:
Sounds like it is running off the accelerator pump charge.


Besides the fuel pump, I am really thinking it could have something to do with ethanol. What can I do to remedy the effects of ethanol in storage?

Pismo
04-16-2010, 05:49 AM
Fuel issue. Stand pipe plugged, fuel pump dying, fuel line rotted away/collapsing, qjet clogged up, the qjet hates dirt but usually it effects the idle most, filters plugged. Alternate fuel supply will rule out tank, line issues. Remove line from tank at water sep, attach short piece, stick end in a can of gas, run, if problems solved then standpipe, fuel line problem. If not other downstream. Get Gumout spray down all those little holes in the qJet. Take top off and do same if so inclined, lots of little parts in the QJet.

WifeHatesMyDonzi
04-16-2010, 06:14 AM
I'd say the root of the problem is from not running in the 2009 season :outtahere::outtahere:


LOL Cut, I'm on Ft Loudon in the Poland Creek area and will be within reach this weekend if you take her out and have trouble. I will be doing "chores" around the house sat and sun, so if you need a tow give me a call and I'll be there. steve 414-2031

RedDog
04-16-2010, 10:43 PM
LOL Cut, I'm on Ft Loudon in the Poland Creek area and will be within reach this weekend if you take her out and have trouble. I will be doing "chores" around the house sat and sun, so if you need a tow give me a call and I'll be there. steve 414-2031


I hope to have my tow-boat out on the water Saturday for her maiden 2010 outing - call as required

Donzi Vol
04-16-2010, 11:48 PM
I hope to have my tow-boat out on the water Saturday for her maiden 2010 outing - call as required

Do what now? I'll be out tomorrow...give me a shout if you want to go for a boat ride (she's running nicely this season!)

Cutwater, all good advice here. Sounds to me like something is clogged. I had a similar problem in the blue 18 a couple seasons ago and it was fuel line problems. There was a bunch of dirt, water, and old gas running through the fuel. We cleaned all the lines, rebuilt the carb, and put in a new in-line filter and no more problems after that. Hopefully yours is that simple. If it's the fuel pump...you know who to call :yes:

cutwater
04-19-2010, 01:12 PM
Haha, thanks Knoxville guys. I (wisely) decided not to risk it on the lake. Ran on the hose after emptying fuel lines, fuel filter, and cleaning out the carb fuel filter (IT WAS DISGUSTING!!) Thanks MrFixx. However, it still does the same thing. :garfield: Good idle for a while, but can't go more than 400 RPMs past idle.

Then after a few minutes, I can't even get it to idle. I have to wait 10 minutes or so to get it to idle again.

I think I'm going to replace the fuel pump and see if that fixes it.


Dirty Jets or water in the float bowl. ETHANOL:doh:
Sounds like it is running off the accelerator pump charge.


... qjet clogged up, the qjet hates dirt but usually it effects the idle most ... Get Gumout spray down all those little holes in the qJet. Take top off and do same if so inclined, lots of little parts in the QJet.

This still bugs me, though... If the fuel pump doesn't fix it, I guess I'll plan on cleaning the carb really well.

VetteLT193
04-19-2010, 03:06 PM
If you are going to change it anyway I suggest going electric. It works much better than mechanical.

before changing it: Do you smell gas in the oil? that is generally the big clue if the mechanical pump is bad. you can do a cranking test to check the output. take off the hose, put it in a container, and crank the engine over. see how much output there is.

mrfixxall
04-19-2010, 03:12 PM
Haha, thanks Knoxville guys. I (wisely) decided not to risk it on the lake. Ran on the hose after emptying fuel lines, fuel filter, and cleaning out the carb fuel filter (IT WAS DISGUSTING!!) Thanks MrFixx. However, it still does the same thing. :garfield: Good idle for a while, but can't go more than 400 RPMs past idle.

Then after a few minutes, I can't even get it to idle. I have to wait 10 minutes or so to get it to idle again.

I think I'm going to replace the fuel pump and see if that fixes it.



This still bugs me, though... If the fuel pump doesn't fix it, I guess I'll plan on cleaning the carb really well.


pull the line off the carb,get a plastic 1 gallon jug,have someone crank the engine over while observing how much fuel is pumping in the jug,,,if its vary little then replace the fp...if its good,it should squirt fuel 3-4 feet then pull the carb and rebuild it..

MOP
04-19-2010, 03:42 PM
Throw the bronze rock away, either run without or put the paper element in place of it! The bronze may look bristol clean, they are somewhat restrictive brandy new, a tad of varnish and they are junk. I do not run any at the carb filters just the Merc canister with no issues.

cutwater
05-14-2010, 03:38 PM
Okay guys. Been busy, but have tried most of the suggestions. I replaced the fuel pump, and this time it ran okay for a couple of minutes on the hose, but then again once warm it was back to the same. Starts to sputter & then cuts out when I take the throttle to about 400 RPMs above idle. I ran it on the gas can straight into the fuel pump, still the same thing.

Then after about a few minutes (I'm guessing closer to the operating temp range) it has trouble even idling.

Does it sound like the carb needs to be rebuilt? Anything else it could be, such as the distributor, or maybe a bad spark plug or wire (and I'm not hearing it missing at idle for some reason)?

I'm clueless when it comes to the carb. Been trying to find a mechanic who knows how to rebuild carbs here in Knoxville but most of the people I've used before are EFI guys. Any thoughts?

mrfixxall
05-14-2010, 04:11 PM
Okay guys. Been busy, but have tried most of the suggestions. I replaced the fuel pump, and this time it ran okay for a couple of minutes on the hose, but then again once warm it was back to the same. Starts to sputter & then cuts out when I take the throttle to about 400 RPMs above idle. I ran it on the gas can straight into the fuel pump, still the same thing.

Then after about a few minutes (I'm guessing closer to the operating temp range) it has trouble even idling.

Does it sound like the carb needs to be rebuilt? Anything else it could be, such as the distributor, or maybe a bad spark plug or wire (and I'm not hearing it missing at idle for some reason)?

I'm clueless when it comes to the carb. Been trying to find a mechanic who knows how to rebuild carbs here in Knoxville but most of the people I've used before are EFI guys. Any thoughts?


Ok i see you have several boat's,i know its a pain in the booty to do this but lets start with process of elimination..

try swapping carburetors with one of your other boats,worst cost would be a 8 dollar base gasket..

if that don't do it look into the ignition,should be a bright blue spark,swap coils,

if that don't do it the pick up or hall effect sensor in the distributor could be going out..Replace it with the new design..

failed to mention,before you do anything above check and make sure the coil wire is in good operating condition,look in the coil its self and look for corroded distributor cap terminals,,

Brian41
05-14-2010, 05:38 PM
Did you try the volume check into a clear jug after the new fuel pump? If not you NEED to do it. If volume is low take a look at the check valve in the gas tank to see if it is plugged and working properly before you do anything else. Also remove the ends of the fuel lines and make sure there are no restrictions.If that is fine the tear down the carb.

Cuda
05-14-2010, 09:22 PM
If you are going to change it anyway I suggest going electric. It works much better than mechanical.
before changing it: Do you smell gas in the oil? that is generally the big clue if the mechanical pump is bad. you can do a cranking test to check the output. take off the hose, put it in a container, and crank the engine over. see how much output there is.
If you have gas in the oil, you are creating a bomb. The bearings will overheat for lack of lubricatiom, then BOOM.

MOP
05-15-2010, 07:31 AM
The Qjet is a fairly simple carb to rebuild, I think Clymers may have a run down. Most any old GM mechanic can do one over for you, most carbs look ominous but end up being fairly easy to do over.

http://www.superchevy.com/technical/engines_drivetrain/induction_poweradders/sucp_0710_qudrajet_carburetor_rebuild/photo_07.html

http://vetteprojects.com/kstyer/quadrajet.htm

http://vetteworks.tripod.com/qjet.htm

You can find a ton of info on the web, don't worry about throttle shafts issues, that only shows up in automotive use after many miles. Think of how many times the throttle position is moved in a car compared to a boat. Once off outside of cleaner tank time most anyone can do one over in about 1-1/2 hour.

Pismo
05-15-2010, 12:16 PM
I love the QJet, those tiny primary and huge secondaries. Good on fuel when slow. Rebuilt many. Lots of little holes and little parts and when QJets get clogged up it usually affects the idle first. I would still look for another cause.

MOP
05-15-2010, 12:44 PM
Put a vacuum gauge between the tank and the fuel pump, with an anti siphon valve you will have approximately 3psi + or - of vacuum. Anything above 5psi vacuum the tank pickup is suspect, at 5 you are not supplying enough fuel for WOT. Test from idle to about 3,000.

cutwater
05-15-2010, 12:58 PM
Thanks guys. Will do. Someone suggested water in the float bowls. Sound reasonable? How do I drain those without pulling the carb?

Pismo
05-15-2010, 01:25 PM
Plugged tank vent. Long shot, but easy to fix. Remove filler cap to test.

Planetwarmer
05-15-2010, 02:14 PM
From what you are describing, I bet a jet is clogged. If it were me, I would pull the carb off and rebuild it. Its only 4 (give or take) nuts and a couple of clips to pull the carb. Its a 5 minute job. It sure wouldnt hurt. I like to take my carbs up to a local motorcycle shop after Ive completely disassembled them, and have them throw them into a vibrating vat. You would be surprised how a jet can look clean, but actually be clogged. Then I would replace the fuel filter with an in-line paper filter with a clear plastic housing so that you can see contaminants.

You probably could walk right in and get a rebuild kit from Oriely's, Napa, or Autozone.

Planetwarmer
05-15-2010, 02:18 PM
Thanks guys. Will do. Someone suggested water in the float bowls. Sound reasonable? How do I drain those without pulling the carb?

The water in the float bowls should be flushed out quickly while you run the engine. Water in a float bowl usually shows up on start up (or lack thereof). Think how many gallons of fuel flow through the float bowls, even when idling. The water would be pulled into the engine almost instantly.

joseph m. hahnl
05-16-2010, 08:11 AM
The water in the float bowls should be flushed out quickly while you run the engine. Water in a float bowl usually shows up on start up (or lack thereof). Think how many gallons of fuel flow through the float bowls, even when idling. The water would be pulled into the engine almost instantly.

Water becomes congealed in the presence of gas. Also the hydrogen moleculesl do not let go of each other forming a glob that is to large for the jet to pass. That is why you add Dry gas to break up the water into smaller parts that can pass through the jets.

Dry gas will remove most water. But when ethenol Phaze seperation is the culprit. The float bowls need to be evacuated and dried with compressed air.

A 4bl carbuerator uses 3 circuits Idle, primary and secondary

The fuel at idle is usually supplied by a transfer slot at the botton of the venturi. As the butterfly plate passes by the transfer slot the vacume increases and the primary jets take over. As more vacume enters the venturi at higer RPM the secondary blutterfly plate will open and the 2nd set of main jets will start atomizing fuel .

1st, Check that the choke stove is working properly.
If the choke is opening .Take the carb off and clean it.

VetteLT193
05-17-2010, 09:10 AM
does the choke open? if it starts and you are running off a fresh tank it shouldn't be fuel to there.

My guess is the choke is stuck or a float is stuck.

did you blast the inside of the carb with some carb cleaner?

Cuda
05-17-2010, 09:31 AM
A four stroke engine won't digest water very well. A two stroke will.

Pismo
05-18-2010, 11:56 AM
With the flame arrestor on, while it is sputtering, spray a little spurt of gumout in the flame arrestor. NOT ether, to explosive. Gumout is basically gasoline in a spray can. If it catches and runs good for a second then you know for sure it is a fuel problem.

DonziJon
05-18-2010, 12:26 PM
Re reading all the posts, I think it comes back to ETHANOL crap clogging up the little jets, gallery's, and passages in the carb. If you squirt something into the mouth of the carb.. Gumout or anything else that will burn, (I use propane from a Bernzamatic)... and the engine comes to life for a bit.. This is just bypassing the jets in the carb.. and the engine will respond.

The jets are still clogged with ETHANOL byproducts. Fuel is not the problem.

Just about everything has been discussed and Tried...except opening the carb and cleaning it out. :lookaroun:

cutwater
05-18-2010, 12:38 PM
Re reading all the posts, I think it comes back to ETHANOL crap clogging up the little jets, gallery's, and passages in the carb. If you squirt something into the mouth of the carb.. Gumout or anything else that will burn, (I use propane from a Bernzamatic)... and the engine comes to life for a bit.. This is just bypassing the jets in the carb.. and the engine will respond.

The jets are still clogged with ETHANOL byproducts. Fuel is not the problem.

Just about everything has been discussed and Tried...except opening the carb and cleaning it out. :lookaroun:

Yep :) You know what I'll be up to this weekend! Thanks for the responses, EVERYONE. I really appreciate all of the help on this site. This will be my first venture into the world of carburetors... :thumbsup:

DonziJon
05-18-2010, 01:22 PM
Check these VIDEOS out and see if it helps you get a feeling for what's involved in a Marine QuadraJet Rebuild :yes: Go back to the first post.

http://www.clubsearay.com/forum/showthread.php?p=285046

cutwater
05-18-2010, 03:27 PM
Nice vids. Thanks.