[GMCnet] Dead coach

[Steve Southworth via Gmclist]

Drove 220 miles. Coach was running just fine. Gas stop about 50 miles before stop. Everything running OK. Stopped for the night. Next morning no
start other than a brief cough and die. Since then nothing. I had a somewhat complicated fuel system. It has been reconfigured to KISS. In tank
pumps to filter to check valve to carb. Got fuel to carb as accel pump does the squirt thing. Got spark at distributor. Went so far as to have a
carb shipped in. This carb was running a GMC just fine a week ago before it was replaced by EFI. Patterson engine and distributor with 20k on them.

I know this has got to be something very simple. I just don't know what it could be.

Oh great collective brain trust, got any ideas.


--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

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[Steve Southworth via Gmclist]

midlf wrote on Wed, 16 October 2019 12:41

> Drove 220 miles. Coach was running just fine. Gas stop about 50 miles before stop. Everything running OK. Stopped for the night. Next morning
> no start other than a brief cough and die. Since then nothing. I had a somewhat complicated fuel system. It has been reconfigured to KISS. In
> tank pumps to filter to check valve to carb. Got fuel to carb as accel pump does the squirt thing. Got spark at distributor. Went so far as to
> have a carb shipped in. This carb was running a GMC just fine a week ago before it was replaced by EFI. Patterson engine and distributor with 20k
> on them.
>
> I know this has got to be something very simple. I just don't know what it could be.
>
> Oh great collective brain trust, got any ideas.

BTW we're at Logansport IN.

[Nelson Wright via Gmclist]

Timing chain ?

Sent from my iPad

[Steve Southworth via Gmclist]

Nelson wrote on Wed, 16 October 2019 12:59
> Timing chain ?

I never say never. Could be but I doubt a Patterson engine would slip a tooth.

I have a timing light along. Can that be used on a cranking engine to check the timing?

[Terry via Gmclist]

Distributor rotor or contact gave up?
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

[Terry via Gmclist]

Make sure there is spark at end of plug wires...

[Emery Stora via Gmclist]

What do you mean “spark at distributor”? Do you have spark at the end of the wire going to the spark plug?

Does your choke work?

Emery Stora
77 Kingsley
Frederick CO

[Steve Southworth via Gmclist]

Bullitthead wrote on Wed, 16 October 2019 13:19

> Distributor rotor or contact gave up?

I pulled the cap to see if the dizzy went round and round. It did. I'll check again looking for those items.

Fortunately we are at a vey nice campground. Parts stores and other shopping easily available. Thank heavens for the toad.

--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

[Matt Colie via Gmclist]

midlf wrote on Wed, 16 October 2019 13:41

> Drove 220 miles. Coach was running just fine. Gas stop about 50 miles before stop. Everything running OK. Stopped for the night. Next morning
> no start other than a brief cough and die. Since then nothing. I had a somewhat complicated fuel system. It has been reconfigured to KISS. In
> tank pumps to filter to check valve to carb. Got fuel to carb as accel pump does the squirt thing. Got spark at distributor. Went so far as to
> have a carb shipped in. This carb was running a GMC just fine a week ago before it was replaced by EFI. Patterson engine and distributor with 20k
> on them.
>
> I know this has got to be something very simple. I just don't know what it could be.
>
> Oh great collective brain trust, got any ideas.

Steve,

Yes, use the timing light.
You know it has fuel, so I vote for an ignition issue. Has it been converted to HEI? If that is the case, suspect the ignition. So, hook up the
timing light and if it is at all irregular, then suspect something in the HEI.

I kind of hate to tell you this, but checking spark by pulling a wire is enough to kill an HEI. If it is dead, the timing light won't flash.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

[Steve Southworth via Gmclist]

[quote title=Matt Colie wrote on Wed, 16 October 2019 13:33]midlf wrote on Wed, 16 October 2019 13:41

> Steve,
>
> Yes, use the timing light.
> You know it has fuel, so I vote for an ignition issue. Has it been converted to HEI? If that is the case, suspect the ignition. So, hook up the
> timing light and if it is at all irregular, then suspect something in the HEI.
>
> I kind of hate to tell you this, but checking spark by pulling a wire is enough to kill an HEI. If it is dead, the timing light won't flash.
>
> Matt

Pertronics. I did not open circuit the HV but had a screwdriver to ground acting as a spark gap. Timing light will tell if it's toast.

I carry a complete spare distributor.

--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

[Todd Sullivan via Gmclist]

Filled with diesel by mistake?

Sully
Bellevue wa

[Jon Roche via Gmclist]

Anybody reading this. an inductive Timing light is a very inexpensive tool that can be very handy to quickly see if you are dealing with a spark or
fuel issue. simplest way I have found to make sure you have spark for sure, without tearing apart things.


So do as Matt and others suggested, hook up the timing light, and zip tie the trigger and crank the engine. That will very easily and quickly tell
you if you have spark. a litte twisting and con-torsion and you can double check it is sparking near TDC.


another easy thing to try, is to use a mustard squeeze bottle, to fill up the carb.

I would suspect a wire on the distributor or such causing an issue. if you are pertronixs, there are a few ways to wire that up on the old points
system where you have to deal with resistor and the extra wire off starter, that could be causing some issue. you need to make sure you know what
voltage the distributor is getting at ignition "on" as well as what it sees while cranking.


--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/

[Dave Stragand via Gmclist]

Just because you saw fluid spray in at the carb doesn’t mean it’s fuel. Can you try some starter fluid Instead?

Sometimes water or separated alcohol accumulates at the bottom of the tank and gets sucked up on cranking.

[Steve Southworth via Gmclist]

sgltrac wrote on Wed, 16 October 2019 13:52

> Filled with diesel by mistake?
>
> Sully
> Bellevue wa

I would say "how in the hell could someone do that". That is until my FIL did that on a trip from Stugis. He got pumped out and filled up. We made
him ride tail end of the pack. His bike just stunk of diesel. Took about two tankfuls before it got to be acceptable, but still noticeable.

Nope - no diesel. Station I filled up at didn't have diesel. When I was working on the fuel system it only smelled like gas.

[Steve Southworth via Gmclist]

lqqkatjon wrote on Wed, 16 October 2019 14:09

> Anybody reading this. an inductive Timing light is a very inexpensive tool that can be very handy to quickly see if you are dealing with a
> spark or fuel issue. simplest way I have found to make sure you have spark for sure, without tearing apart things.
>
>
> So do as Matt and others suggested, hook up the timing light, and zip tie the trigger and crank the engine. That will very easily and quickly
> tell you if you have spark. a litte twisting and con-torsion and you can double check it is sparking near TDC.
>
>
> another easy thing to try, is to use a mustard squeeze bottle, to fill up the carb.
>
> I would suspect a wire on the distributor or such causing an issue. if you are pertronixs, there are a few ways to wire that up on the old
> points system where you have to deal with resistor and the extra wire off starter, that could be causing some issue. you need to make sure you know
> what voltage the distributor is getting at ignition "on" as well as what it sees while cranking.

Pertronix is wired like HEI. Direct from ignition switch. Resistor wire is no longer used.

Spouse can do the cranking while I attempt to see the marks.

--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

[Todd Sullivan via Gmclist]

Well that is good news for sure. I know unlikely but if you had spark and
fuel and no fire.........

Sully

[Steve Southworth via Gmclist]

Emery Stora wrote on Wed, 16 October 2019 13:24

> What do you mean "spark at distributor"? Do you have spark at the end of the wire going to the spark plug?
>
> Does your choke work?
>
> Emery Stora

Pulled wire from coil off at distributor and did the check there.

Yes - it sets correctly and starts to come off (electric) with the key on.

[Steve Southworth via Gmclist]

Dave Stragand wrote on Wed, 16 October 2019 14:13

> Just because you saw fluid spray in at the carb doesn't mean it's fuel. Can you try some starter fluid Instead?
>
> Sometimes water or separated alcohol accumulates at the bottom of the tank and gets sucked up on cranking.

During the simplification of the fuel system there was some fuel in a catch pan. It evaporated and left no trace of any liquid. Coach has been run
a fair amount since August so I don't think it was alcohol separation. Carb smells very strongly of gas just like expected.

--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

[Johnny Bridges via Gmclist]

You describe a lack of spark. Figure the liquid coming down the carb throat is in fact gasoline then a lack of spark to light it is highly indicated.
Check with the timing light and report back. Or just hazard ten bucks and buy a new ignition module. Worst case it's a spare to have on hand.
Advance or any of them ought to have a light for lend.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

[Steve Southworth via Gmclist]

One thing not mentioned. I have a 455 but the carb is off a 403.

From what I can tell it should not make a difference. At least for starting. Air moves past a Venturi and sucks out enough gas to make the proper
mixture. ?????

[Steve Southworth via Gmclist]

Johnny Bridges wrote on Wed, 16 October 2019 15:32

> You describe a lack of spark. Figure the liquid coming down the carb throat is in fact gasoline then a lack of spark to light it is highly
> indicated. Check with the timing light and report back. Or just hazard ten bucks and buy a new ignition module. Worst case it's a spare to have
> on hand. Advance or any of them ought to have a light for lend.
>
> --johnny

Pertronix module.

Checked with timing light. No flash. Pulled spark plug (#7) grounded it and saw very weak spark (amber) with only an occasional blue one. I will
test the timing light on the toad to determine if it is working.

--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

[Dave Stragand via Gmclist]

That's not really ideal -- carburetors are set up for specific
applications. Even a 455 car carb is set up quite differently from a
455 GMC Motorhome carb, so a 403 carb will be different as well.
However, it should still start & run.

I'd still check the spark as folks had mentioned, and also would still
give it a quick shot of starter fluid just to be sure it isn't related
to poor fuel.

It is cranking over at a fast enough speed when you turn the key,
correct? I don't think that was mentioned, so best not to assume.

Does the oil pressure look okay when cranking, and have you checked the
oil level? (This can be an obscure, lifter-related cause of a
no-start).

-Dave
1978 Transmode near Pittsburgh

[Larry via Gmclist]

Steve,
I had a similar situation on a cold restart. Also have a pertronix type pointless ignition. There are two types of Pertronix. One type has a ring of
magnets mounted under the rotor and sensor on the points plate. Part #1181. Magnet passing the sensor triggers spark. The other type has just a
sensor that triggers off of the distributor cam lobes. Part # 1181LS (LS is Lobe Sensing) Mine had the ring of magnets type, and one of the magnets
dropped out and wiped out the trigger mechanism....no spark. If you find one of the magnets missing, from the ring, that is probably the problem of
no spark. If that is the problem, replace it with the PerTronix 1181LS....NOT the 1181. See this link:

https://www.amazon.com/sk=pertronix+1181&gclid=Cj0KCQjw_5rtBRDxARIsAJfxvYAQtQFGvEmU8uaAl_2d2PNroDw5YZY5sC93XSo7EHXGMxwjB8pecwUaAuh7EALw_wcB&hvadid=174254216159&hvdev=c&hvlocphy=9019332&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=9664558291525399405&hvtargid=aud-646675773986%3Akwd-4196625802&hydadcr=7467_9322228&tag=googhydr-20&ref=pd_sl_63rx6cmyl9_e.

If this is the problem also check your coil. This problem somehow sent full time juice to the coil and boiled my coil. Ended up getting this coil.
https://www.summitracing.com/parts/pnx-40011

Also check the braided wire that grounds the points plate to the distributor body. Found mine broken.

HTH
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.

[Rich Kinas via Gmclist]

I had a similar problem with my coach when I was originally bringing it
home. I swapped the plugs and closed the gap (to assist a weak spark), it
fired right up and ran perfectly.

Rich

On Wed, Oct 16, 2019 at 6:24 PM Larry via Gmclist <gmc...@list.gmcnet.org>
wrote:

[Ken Burton via Gmclist]

Steve, call me at home if you need help. My number is on the Black list.
A GMCer helped me 80 miles away last Thursday and that is about what Logansport is from here. So I am just paying it forward. If there is no answer
here, I will be outside with my backhoe digging holes and planting trees. SPEAK SLOWLY to my voice mail and repeat any numbers twice.

Ken B.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Steve Southworth via Gmclist]

KenB - Update. I got the GMC running only to find out I have a completely blown out LH exhaust manifold gasket. I've picked up a new one and will
be, hopefully, getting it installed this morning. I'll also email you as my hearing is also not so great.

Thanks to everyone for help so far. When this is all done I'll publish a forensic analysis of this whole topic.

Ken Burton wrote on Thu, 17 October 2019 23:10

> Steve, call me at home if you need help. My number is on the Black list.
> A GMCer helped me 80 miles away last Thursday and that is about what Logansport is from here. So I am just paying it forward. If there is no
> answer here, I will be outside with my backhoe digging holes and planting trees. SPEAK SLOWLY to my voice mail and repeat any numbers twice.
>
> Ken B.


--

Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

[Ken Burton via Gmclist]

OK Steve,

If you need anything, call me. Email is OK but like normal snail mail, I only check it occasionally. The telephone will get a you a more immediate
response.

I should be home planting trees today and I should be around the Valparaiso Airport on Saturday and Sunday. Call my home first. I do not live with
my cell phone and I leave it in my car, sometimes for days, between use. (two 1 Nine - two 6 three - eight 1 seven 4)

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Steve Southworth via Gmclist]

I still was having trouble. Appeared to be timing. After consulting MattC a few times and futzing with various settings it was running. Strange
setup however. 12degrees initial timing at 600rpm, no vac advance. Am i happy with it? No. But it will get me to the next stop. With vac advance
connected there is exhaust backfire.

Do I know or understand what is going on here? No.

[Emery Stora via Gmclist]

12 deg May be a little too much. With vacuum advance connected you are over 12 deg. Try setting vacuum advance a little lower. Try 8deg and then hook up the vacuum and see if it still backfires.

Emery Stora
77 Kingsley
Frederick, CO

[Jim Kanomata via Gmclist]

--
Jim Kanomata
Applied/GMC, Newark,CA
ji...@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502

[Jim Kanomata via Gmclist]

I think you went to Manifold Vac. , your to go to Throttle Vac.
If you need it explained, call me.

[Ken Burton via Gmclist]

JIM,

He is going to be stopping by here tomorrow. That is is one of things we will be checking. Also will check for a slipped harmonic balance outer ring
and several other things.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

[Jon Roche via Gmclist]

I personally think you might now be dealing with two things. spark and fuel.

my guess would be you now have spark, but your carb is not giving enough fuel (lean out backfire). your timing setting is not far enough off to
cause the backfiring the way you are describing it. Ken should be able to help you pretty well, He has has performed miracles on some GMC's.
I would be apt to get a boat tank out and try to feed it some unrestricted good fuel.

your carb is wrong, but if it was working prior, it should work well enough now. talk to your friend Ray, he will probably convince you to
install a Holley sniper once you get home.

--
Jon Roche
75 palm beach

EBL EFI, manny headers, Micro Level, rebuilt most of coach now.

St. Cloud, MN
http://lqqkatjon.blogspot.com/