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HELP! Serious running issues!  Rating:  Rating
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 Posted: 05-05-2014 07:57 am
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answerman
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Running issues, just when I least expected them.

Figured today was the day for the first outing, since Ms. J is mostly complete other than things like trim and bumpers.

So, charged up her battery, put a few gallons of gas in the tank, and started her up.  Well, mostly.

She's running on maybe 3 cylinders from the sound of it.  No power at all, backfiring like crazy.  Fuel is just pouring out of the front carb.  When I pulled the plugs, #3 was pretty much black and gasoline soaked.  And it's weird, because I haven't done much of anything to her since the last time she ran, about a month and a half ago when I took her to the storage unit, and she ran just fine then.

Here's the laundry list of all related evidence.  Between the last time she ran and today, I have:

- removed the K&N pancake filters and reinstalled the original airbox and filter with a new K&N element.  More on this below.

- capped off the unused port on the charcoal canister, which never had been capped.

- had the fuel tank repaired and reinstalled it.

What I did to try to correct:

- It appears that I seriously overoiled the element, which I initially figured was the problem as the engine couldn't breathe.  So, I removed the whole airbox assembly from the car and cleaned it with the K&N cleaner.  While it was soaking, I tried running the car without the any of the airbox assembly installed.  Made no difference.

- pulled and refitted all the plug wires.  Then, pulled the distributor cap and inspected.  All is clean and tight.

- pulled all the plugs and replaced them with new.  No change.

- ran a half can of Seafoam Engine Cleaner (spray) through both carbs.  Made lots of smoke, but didn't solve anything.

- pulled all the plugs again, let them dry (they were soaked in gasoline) and while they were out ran a quick compression check.  From front to back, #1 and #2 were at about 100 while #3 and #4 were about 120.  I've never checked it till now so I don't have a baseline as to what it was before.

I'm stumped.  Like I said, nothing has really changed since the last time she ran.  It sounds like an ignition or timing issue to me (since she seems to be getting plenty of fuel judging from the way it's pouring from the carb and there's no issue of air blockage with the air cleaner removed).  But, I haven't touched anything to do with the ignition or timing.  Next step would be to check for spark at all plugs, which I haven't done yet.

Would (let's use the word "seriously" here) over oiling the K&N element potentially cause such a thing?  Did all that lovely red oil get sucked into the carbs and cause havoc?

The only thing left that I can "undo" from my change list is to pull the cap from the charcoal canister, but I can't believe it would make that much difference.

Ideas?  This seriously throws a wrench into my plans to attend the Jensen East meet this month!

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 Posted: 05-05-2014 08:19 am
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subwoofer
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answerman wrote:
Fuel is just pouring out of the front carb.

Your answer is right there, it is drowning in fuel. The question is why, and it will not be ignition related.

To me it sounds a lot like a stuck float or too high fuel pressure overwhelming the needle valve. If you still run Strombergs, this may be a good time to rebuild them. If the membrane in the dome has ruptured the piston will never lift and it will be extremely rich - if it runs at all.

--
Joachim

Last edited on 05-05-2014 08:19 am by subwoofer

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 Posted: 05-05-2014 01:52 pm
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Brett Gibson JH5 20497
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Have to agree with Joachim, it's in your carb's.

 

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 Posted: 05-05-2014 05:36 pm
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answerman
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OK, this is helpful. Thanks guys. The question is how did this happen? Just a coincidence unrelated to everything I posted above? Normally I don't believe in coincidences.

Specifically, looking at the air filter over oiling issue. Do you think it could have had anything to do with it? Because that's really the only thing that changed.

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 Posted: 05-05-2014 05:52 pm
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subwoofer
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Does the fuel flow from the carb while the fuel pump is running, or just while cranking?

I am sort of guessing you have a sunk float, that would just be a coincidence.

- Joachim

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 Posted: 05-05-2014 06:58 pm
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answerman
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I'll look at this later tonight to see when the fuel flows. Did a little research on the Strombergs (still trying to tie what I changed to this)... apparently there is a vent port on the face that needs to vent to atmosphere? Looks like one of the threaded mounting holes (think of the three mounting holes as being at 9, 12, and 3 o'clock positions, with two other holes at about 10 and 2 and the one at 10 being the vent)? When I made my custom gaskets to mount the airbox, I didn't punch any holes other than the three for the airbox mounting holes. So, that would have been blocked (though it's all removed now). Think that might have triggered the event?

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 Posted: 05-06-2014 05:25 am
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answerman
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Whew. Good news for a change. Ms. J is back to running normally. Turned out to be quite the easy fix.

Thanks to Brett and Joachim, I realized that they were right and it was definitely a carb issue. So, this afternoon I did some Web research on Stromberg 175s (which is where my mistaken reference to the vent in the above post came from), and found a few suggestions. I was ready to rip her apart and prepare for a rebuild, when on some Triumph forum someone mentioned that his float got stuck once and he was able to free it with a sharp rap on the bowl with a screwdriver handle.

Tried it when I got home. Instant fix. Not only that, she started easier than she ever has.

My theory, based on a little common sense combined with what I know of carbs and the aforementioned research, is this: because she's been sitting for about 6 weeks with no gas tank and no air filter, all the fuel in the float bowl evaporated. This caused the float to sink to its lowermost point, lower than it would generally get in practice. Because it was a little sticky in there (probably not aided by the K&N oil) it stuck in that bottom position, and when the fuel was reconnected and I tried to run her, the float didn't float back up like it was supposed to. Now that it's free and floating nicely in the fuel, in theory it shouldn't happen again unless the situation were to reoccur (not likely at least for the summer since I intend to be driving her several days a week).

How does that sound to you guys?

Oh btw, turned out I still had the gaskets from the K&N pancake filters, so I just used those to reattach the factory airbox. Not sure why I didn't think of that the first time. And I now realize that the vent is between the 12:00 mounting hole and the throat, not the threaded hole. Not sure how I read that wrong. I've been under a little pressure :-)

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 Posted: 05-06-2014 02:11 pm
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Brett Gibson JH5 20497
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Glad to hear your back up and running, yes you are probably right gas drying out gets thicker and sticky best thing you can do when putting the carbs away if they are open to the atmospher is to drain them, just pulling the plug on the bottoms is the easy way.

As for the vent there are a bunch of Strom's 175's some have the vent (later one's) and some dont and use another path to vent the float bowl's, but if you plug it your car will run for awhile then die out, once the pump refills the float you will be able to drive off again but will keep repeating.

Brett

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