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Ongoing fuel starvation issue '84 GL


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37 replies to this topic

#1 Greenley

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Posted 16 February 2009 - 02:28 AM

1984 GL Wagon 4wd

I went with new fuel filters and also plugs, wires, cap 'n' rotor for kicks.
Still the same occasional fuel starvation issue.

Today, on the way back from the junkyard,
it started up right away as i left the parking lot.
Really bad, could hardly even putt off to the side of the highway.

Popped the hood to look around and noticed the vapor separator
appeared to have a rolling boil inside (it wasn't hot, only air).
Opened the fuel tank cap and it stopped.
Also, when i shut off the motor after running for a while,
i notice a "glug-glug-glug" sound coming from the fuel tank.

This is driving me loopy, as soon as i think it's fixed there it is again.
Makes it tough to diagnose! Any insight into this issue?

#2 Greenley

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Posted 16 February 2009 - 02:32 AM

http://www.ultimates...078&postcount=2

This gives me some clues...

#3 edrach

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Posted 16 February 2009 - 10:06 AM

http://www.ultimates...078&postcount=2

This gives me some clues...

Funny, that's what I was going to say/:) Good job searching!

Actually, I had a similar problem last summer with our Toyota based motorhome. The charcoal canister was plugged with something and caused the same vacuum conditions with the fuel tank. It didn't result in fuel starvation, it actually caused the fuel tank to develop an air-leak to resolve the pressure differential. So add the charcoal cannister to your list of potential suspects.

Edited by edrach, 16 February 2009 - 10:10 AM.


#4 Greenley

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Posted 17 February 2009 - 03:58 PM

I had the vent line coming from the firewall capped after going through with the weber swap (I deleted the canister at that time).
I didn't think it would have any effects, but i was obviously wrong.

It drove great for 40 miles, although i can't quite say it's fixed,
because of the ghost-like nature of the problem.

If it does/doesn't occur in the next week or so, i'll let it be known.

#5 NV Zeno

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Posted 02 May 2009 - 05:26 PM

Hey Pete, has that problem returned/stopped?

There's some talk starting about hitting the PnP in a couple of weeks (May 16-17 or thereabouts) from some of the guys, think you might want to get in on that?

#6 Greenley

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Posted 05 May 2009 - 05:46 PM

Hey Dave,

The problem is still there, but I've pinpointed it to the Weber.
We'll see if the brand new one i've yet to install will do the trick.

#7 TomRhere

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Posted 06 May 2009 - 02:53 AM

http://mshoup.us/doc...Fuel_System.pdf


Scroll down to page 4-29, fig 4-84, look for item #39, (at top of figure near the left center of page).

That is a 2-way valve. It allows fuel vapor to be drawn from tank, and air to enter tank as gas level drops.

You may have damaged the valve when you capped the vent line.

There is info on how to troubleshoot the valve also.

#8 Greenley

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Posted 08 June 2009 - 01:32 AM

Update: I didn't mess with above mentioned part, but thanks for the input Tom

I put on a brand spankin' new Weber, jetted correctly for my altitude.
Awesome low end, but i still cant get above 40 on a consistent basis.

Jerks back and forth when under load in 3rd @ around 2500 rpm.
I am really doubting it's carb related now.
The valve lash could probably use adjusting, but i can rev to 7k just fine.

What would make it run great, then fall flat on it's face?
Vac Advance? PCV not being hooked up ?
HELP!

#9 ferox

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Posted 08 June 2009 - 02:31 AM

Did this start happening when you put the weber on originally and gradually get worse, or did it run great with the weber before and has developed more recently. What kind of vacuum is your vac. advance hooked to? I unfortunately haven't worked with the weber, so I don't know what kind of float adjustments are needed.

Ya know, I recently found that the Fuel Pump Control Unit was bad on my wife's '84. It drove ok until about 2500 rpms in 3rd, then it would start surging. It gradually got worse and luckily died in front of my shop while I was trying to diagnose it. I popped the plastic case of the unit and could clearly see a bad transistor. I've have got another thread with pics I will link to tommorrow when I post some more pics. It's a thought, and quick and easy to pull out and check. Good Luck

#10 Greenley

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Posted 08 June 2009 - 04:53 AM

It ran OK with the old weber for about a week or so, was intermittent, and has gotten progressively worse.
Although with the new carb the low end is much improved,
most likely due to the proper jets.
Nowadays, the "surging" is a regular occurrence at a specific speed/RPM.
like clockwork.

The vac. advance line is routed to an open port on the carb base itself.
I'm sure it's connected properly. Could be a faulty advance mechanism though. I need to look more into testing the advance.

I will also note that my PCV is only half-connected. The passenger side is left open to breathe to atmosphere, whilst the D/S is hooked the PCV valve itself.
I don't have the T's or hose available at this time. Could this be detrimental?

I believe THIS is the link you were speaking of.
Funny, i had replaced the hood release cable around the same time this problem started. I'll investigate the FPCU further.
Thanks for your insight.

Edited by Greenley, 08 June 2009 - 02:25 PM.


#11 Greenley

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Posted 08 June 2009 - 04:04 PM

Just swapped in the FPCU from the brat, so we'll see if that makes a difference. Although the existing units' internals looked fine.

Off for a test and some brew :drunk:

#12 NV Zeno

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Posted 08 June 2009 - 04:41 PM

Just swapped in the FPCU from the brat, so we'll see if that makes a difference. Although the existing units' internals looked fine.

Off for a test and some brew :drunk:



Hey Pete, if you're still around I can meet you at Mott Canyon, or maybe HamDogs.

:drunk:

#13 Greenley

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Posted 08 June 2009 - 08:00 PM

Deng it, i was already gone. Hamdogs would have been nice :slobber:.

Anywho, i swapped FPCU's to no avail.
Top speed 40 mph until the savage bucking continued.

I need more ideas.

#14 NV Zeno

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Posted 08 June 2009 - 09:17 PM

Yeah, Hamdogs..great place for breakfast, too.

Maybe your problem isn't fuel starvation. Could be electrical, possibly a cracked disty cap, or maybe a timing problem..might be worth a check (or double-check).

Just my 2 bucks

#15 subieman

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Posted 09 June 2009 - 06:24 AM

Well pete to be honest with you it sounds like a carburetor issue. I never put a Weber on that wagon just because I was afraid I would never get it running right. Do you still have the original carb? Put it back on and see if your problem goes away. I had this issue you are speaking about, I replace the carb and the problem went away.

Good Luck man

#16 Greenley

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Posted 09 June 2009 - 02:44 PM

It really does sound like a carbie issue.
But after 2 carbs, including one absolutely new, properly jetted and set up, that tells me my problem is elsewhere. Thanks for poppin' in, Jermemy:)


I've confirmed that my vacuum unit has a slowly leaking diaphragm.
When i tested it, the plate reacts sharply to applied vacuum,
but slowly retreats back to its "relaxed" position.

Is this my demon? Do my symptoms match a bad vac unit?
Mr. obvious would say "Try it and find out", but before i shell out the duckets,
i'd like to confirm that this is most likely the cause of my issue.

#17 GeneralDisorder

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Posted 09 June 2009 - 07:41 PM

Is this my demon? Do my symptoms match a bad vac unit?
Mr. obvious would say "Try it and find out", but before i shell out the duckets,
i'd like to confirm that this is most likely the cause of my issue.


It is not your issue. In fact I would guess that the *majority* of carbed Subaru's still on the road have bad vacuum advance pots - I've owned and driven several that never worked. You will notice a slight lack of performance from a bad vac can, but ultimately at WOT the engine isn't using the vacuum advance - it's only used for acceleration and part throttle cruise.

GD

#18 Greenley

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Posted 09 June 2009 - 09:35 PM

Thanks for clearing that up GD.

You know these EA81's very well.
Do you have any opinions on this issue of mine?

Like i mentioned, it runs and idles very well. Pulling hard until 3k RPM in 3rd.
I cannot accelerate any more, i have to feather the throttle to keep that pitiful 40 mph top speed.

Brand new Weber 32/36.
135/135 mains 180/170 air correctors 50/55 idle jets
mixture screw 2 1/4 out.
(i'm @ 5,000 feet+)

Thanks.

#19 GeneralDisorder

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Posted 09 June 2009 - 09:58 PM

Thanks for clearing that up GD.

You know these EA81's very well.
Do you have any opinions on this issue of mine?


Rereading your post, and considering what you have done....

My money is on a severely restricted exhaust. I'm guessing that your catalytic converter has imploded (as they often do) and in your case is clogging up the discharge end of the cat housing or further up inside the muffler or something.

It's worth the time to pull down the y-pipe. Remove the heat shield from the cat, cut a square out of the cat housing with a cut-off-wheel in a die grinder and see what it looks like. If you are lucky the clog is in there and will be easily cleared. Then you just weld the sqaure bit back in place (welds like butter - the cat is stainless!) and put the heat sheild back on - no one is the wiser and if you still need a cat to pass emissions put one of the ebay models in the mid-pipe.

Here's what I mean (from my '83 hatch):

In this first pic - be mindful that you are seeing EXACTLY what I saw when I opened it. This was untouched by human hands since 1983 - I cut it open right before taking this series of pics (I had previously welded the passenger side runner where it cracked clean through, but never opened the cat - you can see my weld in the pic):

Posted Image
Posted Image
Posted Image
Posted Image
Posted Image

In the case of my hatch it wasn't enough of a blockage to cause a severe loss of power - there was some loss of power but more problematic was the loss of freeway mileage - I gained about 3 MPG by clearing that out. Your's may be worse and I could easily see it causeing a lack of power. Mine was largely burned away leaving only the metal bits - but wadded up like that and stuffed into the cat dsicharge there was very little flow and it was causing a lot of backpressure. I too went round and round looking for the answer - decided it had to be something I couldn't see and pulled the y-pipe for an inspect.

GD

Edited by GeneralDisorder, 09 June 2009 - 10:07 PM.


#20 GeneralDisorder

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Posted 09 June 2009 - 10:03 PM

Your jetting may be a bit lean also - that's leaner than I run at sea level anyway - but at 5,000 it might be alright.

For reference, I run:

140/140 mains
170/160 air correctors
50 idle jet(s)

I verified these jets with a wideband O2 sensor and they are very well suited to the EA81. Excelent power when you need it and nice and lean in the part-throttle cruise with no hessitation issues anywhere in the band. In the case of jetting - Redline did a good job picking jets for the kit as I have never had a need to change them.

GD

#21 Greenley

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Posted 09 June 2009 - 10:32 PM

Thanks for the pics, and taking the time to reply.

I've thought of this before, but never acted on it.
Easy enough. I'll try it tomorrow.

Just to add to the above post:

My new in the box carb was $20 from a garage sale :eek:
It was jetted for a Toy 22r when i got it.
I used a combination of your recommendations (search function FTW)
Jerry Demoss' suggestions, and Redline's altitude graph for the final setup.
I feel it is right on. Plugs look right. Low end is A+.

The used weber i had before ran extremely rich for testing purposes,
1/4 tank of fuel in 5 miles. Could have really plugged up the exhaust.
We'll see tomorrow afternoon...

Edited by Greenley, 10 June 2009 - 04:11 AM.
blahblahblizzah


#22 Greenley

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Posted 11 June 2009 - 06:06 PM

Posted Image

It was perfect. Hard to believe for 200k+ miles.
I gutted it out anyway, it was damaged by the cutoff wheel.
No clogs in the rest of the exhaust, flows freely. (shop vac test)


Next :-\ ...

#23 GeneralDisorder

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Posted 11 June 2009 - 06:29 PM

Lets see here.....

Have you checked:

1. Fuel pressure?

2. Ran it with/without the return line?

3. Plug gap?

4. Replaced the plug wires?

5. Any play (side to side) in the disty shaft?

6. Primary and secondary coil winding resistance?

It does sound, from your description, that it's either super lean, or you have an ignition issue causeing it to not fire under load. I've seen similar problems from poorly gapped plugs but you say they are ok. I'm wondering if you have a weak spark....

GD

#24 Greenley

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Posted 11 June 2009 - 06:45 PM

Lets see here.....

Have you checked:

1. Fuel pressure? Definitely adequate for a carb

2. Ran it with/without the return line? Yes

3. Plug gap? .50 (MSD coil) I've tried anywhere from stock to .55

4. Replaced the plug wires? less than 500 miles ago

5. Any play (side to side) in the disty shaft? None, nice and tight

6. Primary and secondary coil winding resistance? Can you expand on this please


It does sound, from your description, that it's either super lean, or you have an ignition issue causeing it to not fire under load. I've seen similar problems from poorly gapped plugs but you say they are ok. I'm wondering if you have a weak spark....

The spark from the coil is orange and spans a gap roughly 3/4 of an inch
when held to bare metal.

#25 GeneralDisorder

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Posted 11 June 2009 - 08:26 PM

This is becoming intollerable that we can't get it figured out. I'm not on the scene so I'm at a disadvantage.

Ok - lets assume for the moment that your issue IS fuel and not ignition.

I propose that you add some new gauges. First though have you performed a comp. test? It would be nice to know that all your cylinders are similar at least.

I would like to see manifold vacuum and fuel pressure. More to the point though I would like to see if there is any changes in either one as you approach the "problem" area of the power band.

As for the coil resistance - if you have swapped the coil to an MSD then any numbers I could give you wouldn't match your coil anyway. But the idea is that you test the resistance of the primary and secondary windings to insure that your coil isn't shorted internally. It's usually less than 10 ohms on one side, and around 10,000 to 15,000 on the other. You test between the two posts (postitive and negative), and between either post and the coil tower.

GD




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