TimWilbers

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84 GSL
Stock, no mods.
Nikki carb.

First, thanks to all those who posted where to find the fuel cutoff relay and what it looked like. The FSM illustrations left much to be desired.

Symptoms:
Rough idle.
Sudden loss of power, then it returns.
It tries to die and stepping on the gas harder keeps it going.
Frequency of intermittent power loss is increasing.

Fuel Pump Pressure Test.
The specs should be 2.84 - 3.44 psi.
Mine came in at about 2.2 psi.

Question:
Could the low fuel pump pressure be a cause of the intermittent power loss?


Other things I've tried.

Ignition related items but no change:
New rotor, distributor cap, spark plugs.
Checked firing on all plugs with timing light.
Switched coils.
Verified correct timing.
Replaced 7 year old battery.

Fuel:
Replaced fuel filter.
Replaced leaking hose leading to fuel filter.

To test the pressure I followed the procedure in the Haynes book.
I borrowed a test kit from O'Rielly. I should have checked the gauge first. I did get a reading but the pressure on the scale was so low it was not possible to read accurately. Fortunately I still have the vacuum/pressure gauge I bought back in 1974 to work on my Rx3. I hooked it in line first, then the O'Rielly one so I could use its pressure release to purge the air out.

t_g_farrell

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Does it do this when cold or warmed up?

TimWilbers

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Both.
When it is warming up with the choke engaged and after running for 30 minutes.

Thanks.

t_g_farrell

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When did it last run well? Was it stored and this is the first outing now after winter?

TimWilbers

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Not the first outing, but soon there after.

I added a can of Seafoam Jan 1 to the gas tank, then started driving it about March 15.

It does blow more white smoke at startup than in December.

t_g_farrell

iTrader: (1)

Well its either an ignition issue or a carb issue. I would lean to a carb issue for now. Try spraying
the carb down with the air cleaner off with a carb cleaner really good, soak it. Let it sit for a bit
and then start it up and get it hot.

If your tank is almost empty I would fill it with fresh gas or run another can of seafoam through it.

Also, see if you can thrash it a bit to redline a few times, could be a sticky seal after sitting.

I doubt the fuel pressure is causing this yet, even with slightly low pressure it should idle
well and drive on the primaries fine. Make sure the bowls are at middle of the site glass too.

TimWilbers

iTrader: (1)

Thanks.
I'm on my second tank of gas.
I did look down the carb last night and the throttle plates on the secondaries looked very gummy. I'll try spraying it some more.
The front bowl does fill to mid-line, I'll need to check the back one.

I have not been letting the carb cleaner soak. I try that too.

(I can't be running it at higher speeds for the moment, my idler arm is shot and steering is not where it should be. Next on the list.)

t_g_farrell

iTrader: (1)

When you parked it did you drain the carb by running it with the pump off till it died? If not the
old gas probably gummed it up pretty good. Especially the gas we have now, it turns to gummy
stuff really quickly these days.

You may need to pull the carb and clean it well. Maybe get rebuild kit but don't use the needles or seats from the kit
and don't mess with the floats if they are working fine.

TimWilbers

iTrader: (1)

No I did not drain the carb

I'll try a massive cleaning first, then rebuild. I don't believe it has been rebuilt in 164k miles.

That would explain the gummy bears on the secondaries.

Thanks for you help. I'll keep the fuel pump as is for now.
I could test the flow to see it is within spec. That's easy enough.

7aull

iTrader: (2)

OR-
If fuel tank is shedding its innards (which would then _usually_ plug the fuel filter. Read on)
then it may be intermittently plugging the fuel outlet in the tank. Does the stall occur with a certain state-of-fill the tank is in? This type of fuel starvation usually shows itself on a low (½ or less) tank. Full tank and crud generally sloshes around in the tank unhindered. As it gets lower, crud can more easily drift to the outlet, plug it, stall out. If it sits for a while (off), the pump stops sucking crud, it drifts away till next start up - or - a filled tank does the same.
This happened on my SA and required a tank drain, pull, clean & reseal with POR15 Gas Tank Kit. PITA but not too hard.
Usually creates crud due to partially-filled tanks put in storage for long periods of time. Air space in tank encourages condensation = rust= innards begin sloughing off into fuel....
this is why you should either fill the tank ab-so-freakin-lootly to the brim for storage (with a can of Seafoam) or drained completely so it sits dry.

Stu Aull
80GS
Alaska

TimWilbers

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Stu,

It has a full tank at the moment, but has been sitting in the garage for more than a week. I'll roll it out when the rain stops and see if the crud has drifted away.

It was 3/4 full when it went for its 10 week sleep with a can of Seafoam added.

Thanks for the tip.

Jeff20B

iTrader: (13)

The Seafoam probably caused some crap to dislodge. I never use that stuff and don't seem to have fuel tank issues.

TimWilbers

iTrader: (1)

Could be, I've put the car to sleep before, but never did use Seafoam.

This is all better than something internal in the engine.

7aull

iTrader: (2)

Seafoam is great for gas stabilization for storage (I still run the carb "dry" of gas tho for winter storage), and also is a great de-carbon additive for the engine itself. 1-can a season (you guessed it: when I put it to bed for the winter).
Other than carbon in the block (which I understand it actually dissolves) I am not aware of Seafood just "dislodging" stuff. Due respect to Jeff, not having used Seafoam AND not having fuel issues sound mutually exclusive.
but every one has stuff they swear by. Or curse.

each to his own...

Stu Aull
80GS
Alaska

TimWilbers

iTrader: (1)

Side issue: my idler arm is shot and steering is less than precise so its not going too far from home.

I'll measure the fuel pump output, but the sight glasses look good.
I'll soak the carb and heat it up stationary, and annoy the neighbors with a few redlines this weekend.
Once I get the steering corrected then I'll be on the road again.

I believe I did notice some "yellow" discoloration at the bottom of the fuel filter before I changed it. I should have kept it for reference as memory tends to fade.

TimWilbers

iTrader: (1)

Fuel pump output in 1 min 1850 cc's.
Carb specs at 1400, fuel injected at 1700.

Both carb floats at mid-line.

TimWilbers

iTrader: (1)

Update:
Soaked the carb. Warmed it up. Redlined multiple times (in first as the idler arm bushings are gone). Seemed to get better till I got to the driveway and the rpm's cut in half and it was idling at about 300.

Also ran into an issue when trying to start it. It almost caught and then no more. Suspected ignition so I attached the timing light to the leading and then trailing coil to dizzy wires. Disconnected the fuel pump relay and cranked the engine. I had ignition on the trailing but not the leading. Then I noticed the plug to the leading igniter was no longer pushed down (the retaining button no longer retains).

Today I noticed the coolant overflow tank was 1/2" low from Full. It remained Full for over a year now it has dropped. This could explain the now massive white smoke at first start up.

Time to rebuild the carb, and check the 0-rings in the coolant passages at the intake manifold.

Jeff20B

iTrader: (13)

You know what I'm gonna say about your carb rebuild, right?

TimWilbers

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Yup.
Need a rebuild kit first and stay away from those needles and floats.

Jeff20B

iTrader: (13)

Seats, my friend. Seats. And needles and floats of course.

TimWilbers

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Thank you.
I'll re-read your posts again.
I have not rebuilt a carb in perhaps 20+ years.