2150 Carb Bowl Draining Overnight

[Brynjminjones]

The past couple of days I've had a new problem with my '91 Wagoneer.
After sitting for a day or two, when I fire it up it will run perfectly for about 5-10 seconds, then completely die.

It will than take about 30 seconds of cranking before it will fire up again. After that it will be perfect all day.


This morning I decided to investigate, so I've taken the top off the carb (original MC 2150) and found it not far from empty.
I parked up at 10pm last night and this was at 8am today, so it's only taken 10 hours to drain this far.

What could be causing the carb to drain this quickly?

Dry carb after 10 hours by Brynjaminjones, on Flickr

[wiley-moeracing]

The gas is boiling out when parked, you need to have a plastic spacer gasket( 1/2 inch or so thick) under the carb to insulate it from the heat of the engine. You can always install a small electric pusher pump for the fuel to the carb to help refill the bowl.

[Brynjminjones]

Thanks, that's an interesting idea that I hadn't considered.

Just having a think about it, if that was the case, surely I would have a similar problem within a shorter time period, not just several hours later?
I've got a similar carb (2100) on our Ford F100 without a spacer, and the bowl on that carb never empties like this.

The Wagoneer never used to do this, but it's now done it the last 3 cold starts.

[Ristow]

Could be the power valve too. Pull the vacuum line of the PV cover and check for gas. Should be none.

[Brynjminjones]

Thanks Ristow, funny you should say that as I've also recently had to replace the power valve in our F100.

I was just starting to suspect the power valve before reading this, so I've just been and looked at the one on the Wagoneer.
With the vacuum line removed there is no obvious sign of gas, but the vacuum line itself did smell of it.

I've also just applied a vacuum to the power valve cover using a hand vacuum pump. I could easily get it up to 20" or so, but leaving it for about 10 minutes it will gradually drop almost to 0.

I assume it should be able to hold a vacuum, and if not it could be the culprit?

[Brynjminjones]

Well, to quote your own signature... "Ristows right.................again" haha

I couldn't resist pulling the carb, so I've just had it off and inspected it.

The whole underside of the carb was soaked in gas which was a good sign we're on the right lines.
I then pulled the power valve cover and had a nice little trickle of gas in there!

I've ordered a rebuild kit to get here in a couple of days' time.
To give you guys in the US an idea of how much it can cost having a Waggy here in the UK, it's $77.99 just for a rebuild kit by the time I've paid for the parts, fast shipping, plus UK taxes! Ouch

[tgreese]

Well, to quote your own signature... "Ristows right.................again" haha

I couldn't resist pulling the carb, so I've just had it off and inspected it.

The whole underside of the carb was soaked in gas which was a good sign we're on the right lines.
I then pulled the power valve cover and had a nice little trickle of gas in there!

I've ordered a rebuild kit to get here in a couple of days' time.
To give you guys in the US an idea of how much it can cost having a Waggy here in the UK, it's $77.99 just for a rebuild kit by the time I've paid for the parts, fast shipping, plus UK taxes! Ouch

Not so bad ... may be double what we'd pay in the States. It's a comparatively expensive kit. The 2-stage power valve is ca $25 by itself. Figure another $25 for overseas shipping plus VAT. Seems about right.

Glad you found your problem. Isn't there a Service Bulletin that moves the vacuum connection to the back of the engine? I presume that's to buffer it better from engine backfire which damages the power valve. Holley adds a ball valve to their carburetors to protect their power valves from backfire. Presumably you could add something like that inline with the vacuum connection.

[Ristow]

the backfire thing is over....um...blown,lol.


here's the problem with motorcraft dual stage powervalves. most are very old stock even in a new rebuild box.


holley powervalves are too short.


Quick Fuel valves are long enough however. i'd get a 6.5 to 8.5" rated valve. i'd get all three since you're in england.

[Brynjminjones]

Thanks both!

tgreese, it's a $36 kit from RockAuto, so it just gets a little painful watching the prices more than double!

The vacuum connection on my 360 already went to the back. I'd thought about shortening the path but maybe I won't now.

I don't think my problem was caused by backfiring anyway though. This Jeep hasn't backfired (to my knowledge!) since 2017 when I first got it!

Ristow, I think you're right that it might be a good idea to have multiple power valves in stock. I just need to find a place that sells them separately and ships over here.


My rebuild kit should be arriving in the next couple of days, so I'll update on here whether or not it does the trick!

[rocklaurence]

Yeah but you have Free Health Care in UK I was in France 15 years ago and a pair of $30 Levis were costing $120 there. I also spent 2 years in Germany [1989-91] and couldnt believe the cost and expense of everything. Plus, over there you cant register a road vehicle if its modified/lifted /has bigger tires etc. No/Nope, Ill pay for my own Health Insurance and Small Government. Not that our Government and Fake News aren't Corrupt--Im not Blind

[Brynjminjones]

Yeah but you have Free Health Care in UK I was in France 15 years ago and a pair of $30 Levis were costing $120 there. I also spent 2 years in Germany [1989-91] and couldnt believe the cost and expense of everything. Plus, over there you cant register a road vehicle if its modified/lifted /has bigger tires etc. No/Nope, Ill pay for my own Health Insurance and Small Government. Not that our Government and Fake News aren't Corrupt--Im not Blind

Haha, yes "free" healthcare straight from my paycheck, although I'll try not to go into a rant about that one!
My girlfriend works in healthcare and it's shocking how badly they get treated sometimes. If they didn't work so many (unpaid) overtime hours I'm convinced it would all fall apart. I've joked for years that she's a glorified volunteer!
On top of that, they have to constantly fight not to have their hours further increased or their pay reduced.

I know the "grass is always greener", but I'd move away from here in a flash!

[Ristow]

Summit or Jegs might ship to england..?

yes "free" healthcare straight from my paycheck,

Bingo!

[Brynjminjones]

I've been doing a bit more playing with this, and I don't think my problem is completely solved.

I've got a new power valve in, and I've not had any issues with starting it in the morning yet. It runs and drives beautifully with no hesitation or smoke.

I wanted to find what jet size I have so I just took the top off the carb again. It's not been driven in since last night (about 18 hours ago) but the bowl was half empty again, although not as empty as before I changed the power valve.

As far as I can tell, the power valve is holding vacuum just fine when I put my hand vacuum pump on it, plus there doesn't appear to be any gas in the vacuum line.

How much gas is normal to lose from the bowl overnight?

[Ristow]

Probably normal evaporation from the hot engine.

[JeepsGot360]

My 2100 and 2150 both do it. I believe having the fuel filter lower than the carb allows the fuel to drain back into the vent portion of the filter. I attached a link that talks about a check valve. https://imgur.com/a/NsIfHE5