Jump to content
Ultimate Subaru Message Board

No combustion - Carb replacement or other solution?


Recommended Posts

When I got her, she drove me home under her own power. Ran well (well enough) for a week. Now she's dead and I can't get combustion… death while cruising (haven't posted about this issue yet)...

 

While cruising at 60mph I heard a loud banging sound from underneath, by passenger's side rear wheel... fuel pump? She hesitated, then five seconds later died entirely, forcing me to coast to the side of the road and eventually get towed home. It was as though it ran out of gas. (had a full tank of fresh gas.)

 

I replaced both fuel filters, and got a new pump. Old one was indeed bad.

 

I thought it would crank right up... nope. I do have spark at the wire/plug junction; got new plugs; have fuel in the bowl… but it won't start up.

:confused:

 

After a little I poured a tad of gas into the carb... it still won’t start up.

 

My next step was to rebuild the carb. It's a Hitachi. :eek:

Since I don’t have a rebuild kit, and am broke as a joke, I followed the “emergency” re-build in How to Keep Your Subaru Alive.

 

I discovered main top gasket was shot, “rubber boot” in accelerator pump torn but the float & needle seemed fine. I gave everything a bath in gas and followed up with carb cleaner in tough spots. Put ever together, and nothing. No combustion. Also, I don’t see gas when the throttle lever is actuated.

 

Some nearby nosy neighbors suggest vacuum leak, others say it may have skipped timing (is that possible?)…

 

I began to think about the gas tank and how I found rust in the filter in front of the fuel pump. But I have gas coming into the carb …?

 

The hoses look good when looking for leaks, shot gasket=vacuum leak?

 

I started to think that the new FP wasn’t pushing enough fuel. I began to think, well everything… all day long and its frustrating as all heck having no $ and just staring at it in my driveway.

 

I am debating my next step…use my tax return to purchase a Weber 32/36 DGEV? I think the $ may arrive in the next week or so. Could this be the solution to all of my woes? (at least get her back on the road?) I really don't want to rebuild the Hitachi, but this would be the obvious cheaper way to go... $25 vs. $339...

 

Please advise.

Link to comment
Share on other sites

Its just cranking on and on, no kick or backfire just turning correct?

The rust and filth in the pre-pump filter is not abnormal, you are sure you are getting a consistant spark? Does the tach bounce while cranking?

Befor you blow money on a weber I'de confirm the carb to be the issue. Honestly even if you removed it and spayed some carb cleaner down the hole youde get some sign of life at least a backfire a kick something, yet you are getting nothing. An internal timing issue is possible you could try to check it. I'de try some carb cleaner sprays befor I'de look too far. A drip of gas down the throat may have not been enough when cold or way too much. Hold the throttle open and spay in there. Also could the banging you heard have been exhaust related?

Link to comment
Share on other sites

Correct, just cranking. After the carb cleaner/gas "treatment" i got a couple of backfires, one up front, one in the rear, seperate attempts.

 

I definitely have a consistent spark.

 

Not sure about the tach.

 

Maybe this is a dumb ques. but how do you check timing without it running?

 

It could have been exhaust related... why do you say? Since reading about FP replacement and seeing that a hammering banging sound would indicate FP failure, I gave it no more thought, esp. since it failed bench test once out.

Link to comment
Share on other sites

Hi '84,

 

An older car such as this will start "without" a carb on it, if you pour some fuel down the open manifold. I don't advise it, but I thought you should know before you throw a new one on it thinking it may solve your problem.

 

Doug

Link to comment
Share on other sites

YOu need suck squish bang to get combustion. Right now all you have is what is required for bang.

 

You need to do a compression test first. Without compression you can rebuild the carb all you want and it wont run. Also carb issues slowly appear over time, and dont suddenly occur with a bang.

 

 

nipper

Link to comment
Share on other sites

Because the only thing that gives you anything is pooring fuel into it I'de say perhaps you need to try a bit more carb cleaner/gas down the carb. It sounds like youre getting fuel but the carb could be plugged up. The banging you heard may just of been backfiring as it starved for fuel. Even if you did jump timing I would think you could still get it started might have to screw with the disty but some sign of life should exist. You could try to eyeball the rotor to point at the no. 1 cyl. and find tdc and see where the marks on the flywheel are at... Another thought when you crank it does it sound normal or is it fast then slow or kicking back?

Link to comment
Share on other sites

1. Perform a compression test. This is essential, and in my opinion should be standard any time a tune up is done or a combustion problem is suspected. This test will show you whether you have enough compression to allow the engine to run, and it will also show you if you have one or 2 low cylinders which could possibly be due to a jumped or broken timing belt, or timing gears on the EA81 Engines, bearing in mind that gears dont usually jump time and then work correctly...

 

2. Check ignition timing. Yes, you can do this without the engine running. Set up your timing light like normal, and just check it with a buddy cranking the engine over. it will still be quite close to correct, if you factor out any ignition advance by the vacuum pot or electronics (depending on which particular car you are working on.)

Keep in mind, if the ignition timing is off, it could once again be due to a jumped or broken timing belt or timing gears.

 

3. Go grab a can of starting fluid. If your compression test comes back OK, and your ignition timing is where it should be, and you have spark at the spark plugs, starting fluid (Ether spray) will make it fire.

 

Nipper put it quite plainly... Suck, Squish, Bang... If it's not sucking, the engine will not draw any fuel / air from the carb. If it's not squishing, it wont compress the mixture enough to let it explode. If there's no spark, or it's in the wrong spot (timing off), obviously there's nothing to light the fuel and make it go bang...

Hope this helps!!

88RxTuner

Link to comment
Share on other sites

After priming it your eyebrows will be in the cab turning the key, so you will probably have to use a razor or some tweezers on your eyebrows. I once tried to check my timing with a light while someone else was cranking, and the light was so dimm and flashes spaced so far appart it really didnt help me much. But it was on a V8 not a 4 so...

Link to comment
Share on other sites

After priming it your eyebrows will be in the cab turning the key, so you will probably have to use a razor or some tweezers on your eyebrows. .

 

 

sooooooooooooo sounds like someone has gone down this route before.

 

i know i can personally attest to the OW OW OW OW method of checking for spark.

 

 

 

nipper

Link to comment
Share on other sites

Further troubleshooting has revealed the following:

 

1) I found that wires No. 1 and No. 3 were reversed. No. 2 & No. 4 were properly run.

 

2) Pointing the disty rotor to No. 1 plug, the flywheel is WELL after. I then turned to have flywheel TDC, and the disty rotor points to No. 4 plug. :confused:

 

3) I think the vacuum/retard unit (attached to disty) is shot. I can move the arm manually & rather easily, but sucking on the hose does not actuate the arm at all. Everything I've read indicates that if it cannot hold vacuum, then it should be replaced.

 

Questions:

Can a failed vacuum unit cause "death while cruising" as I described above?

 

Could the car have run for a week with the wires improperly run (#1 & #3 reversed)?

 

Should I correct timing by rotating the disty to have rotor pointing to No. 1 plug while TDC?

 

Btw, I have a late Hitachi (electronic) breakerless disty.

Also, the mechanical advance works fine; disty shaft has zero play side-to-side.

 

I think I've provided all info I can think of for now. No compression test done yet (no $$ for another week or so). But does the above make sense to you all?

Link to comment
Share on other sites

The vacume advance canister would not cause the car to die. It probably has not woked for a long time. Are you sure the wires were swaped. If they were swaped the car could not have been running well at all.

 

Flywheel

3 4

1 2

Radiator/front

 

Disty

--1

3 c 4

-- 2

It sounds like no. 1 cyl may not have been at TDC. It must be for that to work.

Link to comment
Share on other sites

:banana: :banana: :banana: :banana: :banana: :banana: :banana: :banana:

 

She's ALIVE!!!!!!!

 

That simple little message with the numbers,... no it didn't confuse me, it clarified everything for me...

I unbelievably overlooked the simplest of things. I had a neighbor help me last weekend, and that's when the wires must have been switched. I never bothered to double-check our work, until I read your message. Something didn't seem right, and when I went with your disty diagram, "suck, squish, and BANG" happened! Unbelievable!

 

That banging on the highway must have been the FP. But with the wires all wrong, it never fired, new FP or not...

 

Well, the silver lining is, now I know the Soob much better now. Carb is super clean, I don't need to drop $ on a new carb, spend money on towing or money for a mechanic, know how to check timing, rebuild carb,etc.,etc., etc....

:clap::headbang:

Link to comment
Share on other sites

Because you asked, and no one answered the question properly - to check timing on the engine without it running you set the flywheel to the desired timing (8 degrees BTDC in the case of the EA81's), and then you verify that the distributor rotor is pointing at the #1 plug tower. I have never been more than 1 degree off by "eyeball" method. Incidentally the plug wires can be hooked up in 4 different, yet all correct, ways. It matters only that they proceed counter-clockwise from whichever you chose as #1 in the order 1,3,2,4.

 

GD

Link to comment
Share on other sites

Very good to know GeneralDisorder... thanks.

In this case it was set up incorrectly as 3,1,2,4.

 

While I did do it myself, I really didn't. If it weren't for you guys and your input, I wouldn't have been so persistent & determined. Words can't express how thankful I am for your willingness to share & help.

 

:grin: Going for a drive... :burnout:

Link to comment
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
 Share

×
×
  • Create New...