gmclist@list.gmcnet.org

GMC Motorhome Discussion List

View all threads

Next Noob Question- secondary's not opening

BW
Bill Wevers
Mon, Jul 26, 2021 3:56 AM

I think Jon is on to something.
Maybe it's a plugged fuel filter
after sitting for several months the
gas may be dirty.

Bill Wevers  GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose

I think Jon is on to something. Maybe it's a plugged fuel filter after sitting for several months the gas may be dirty. -- Bill Wevers GMC49ers, GMC Western States 1975 Glenbrook - Manny Powerdrive, OneTon 455 F Block, G heads San Jose
DS
Douglas Smith
Mon, Jul 26, 2021 2:00 PM

When you mention filters, you haven't specifically mentioned the one at the carb. A carb swap would likely get that when it was possibly the only
problem.

Douglas & Virginia Smith,
dsmithy18 at gmail,
Lincoln Nebraska,
’73 “Sequoia” since ‘95: "Wanabizo";
Quadrabag/6 wheel disks/3:70 final/Paterson QuadraJet/Thorley’s/Alloy wheels/Sundry other

When you mention filters, you haven't specifically mentioned the one at the carb. A carb swap would likely get that when it was possibly the only problem. -- Douglas & Virginia Smith, dsmithy18 at gmail, Lincoln Nebraska, ’73 “Sequoia” since ‘95: "Wanabizo"; Quadrabag/6 wheel disks/3:70 final/Paterson QuadraJet/Thorley’s/Alloy wheels/Sundry other
JR
John R. Lebetski
Mon, Jul 26, 2021 2:53 PM

Need more info to solve.  Is this issue happening in the first 1/3 of pedal travel (carb primaries only) or only when you push past that 1/3 pedal
travel and open the secondaries. You should be able to feel the resistance of pushing against the secondary return spring so you know when you are
starting to open the secondaries for reference.

John Lebetski
Woodstock, IL
77 Eleganza II

Need more info to solve. Is this issue happening in the first 1/3 of pedal travel (carb primaries only) or only when you push past that 1/3 pedal travel and open the secondaries. You should be able to feel the resistance of pushing against the secondary return spring so you know when you are starting to open the secondaries for reference. -- John Lebetski Woodstock, IL 77 Eleganza II
DS
dave silva
Mon, Jul 26, 2021 5:23 PM

Yes, i have changed the main filter and the filter on the carb.

I recently opened the distibutor and swapped out the control board and the coil.  timing advance looks good.

Also, when i rev it with a timing light on i can se it advance.

It is possible the timing is messed up.

On the first 1/3 of pedal travel it runs great and accelerates very slowly.

It bogs down when i try to go past that, no matter how gentle i am.

This problem have been  slowly getting worse over the last 200 miles. (all short test drives)

--
Dave & Ellen Silva
Hertford, NC

76  Birchaven, 1-ton and other stuff

Currently planning the Great american Road Trip Summer 2021

It's gonna take a lot of Adderall to get this thing right.

Yes, i have changed the main filter and the filter on the carb. I recently opened the distibutor and swapped out the control board and the coil. timing advance looks good. Also, when i rev it with a timing light on i can se it advance. It is possible the timing is messed up. On the first 1/3 of pedal travel it runs great and accelerates very slowly. It bogs down when i try to go past that, no matter how gentle i am. This problem have been slowly getting worse over the last 200 miles. (all short test drives) -- Dave & Ellen Silva Hertford, NC 76 Birchaven, 1-ton and other stuff Currently planning the Great american Road Trip Summer 2021 It's gonna take a lot of Adderall to get this thing right.
DS
dave silva
Tue, Jul 27, 2021 8:09 PM

A very wise GMCer PM'd me suggesting it might be a cracked intake manifold.

That fits perfectly with the symptoms.

While the coach had a slew of problems related to sitting for a long time; each time i fixed one (fuel filter, bad gas, etc) I would get a slight
improvement but overall the problem kept getting worse no matter what else got better.

This seems to line up perfectly with a crack that is growing with each heat cycle.

I have not had a chance to back and test for this (ether?)

--
Dave & Ellen Silva
Hertford, NC

76  Birchaven, 1-ton and other stuff

Currently planning the Great american Road Trip Summer 2021

It's gonna take a lot of Adderall to get this thing right.

A very wise GMCer PM'd me suggesting it might be a cracked intake manifold. That fits perfectly with the symptoms. While the coach had a slew of problems related to sitting for a long time; each time i fixed one (fuel filter, bad gas, etc) I would get a slight improvement but overall the problem kept getting worse no matter what else got better. This seems to line up perfectly with a crack that is growing with each heat cycle. I have not had a chance to back and test for this (ether?) -- Dave & Ellen Silva Hertford, NC 76 Birchaven, 1-ton and other stuff Currently planning the Great american Road Trip Summer 2021 It's gonna take a lot of Adderall to get this thing right.