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01-11-2019, 06:10 AM
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#61
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3 Rivet Member
1986 32.5' Airstream 325
Merritt Island
, Florida
Join Date: Nov 2018
Posts: 122
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Quote:
Originally Posted by bkahler
I haven't looked at my throttle body while revving the engine but I'm wondering if you're getting to much fuel which is bogging the engine down?
Unfortunately I'm not in a position where I can start my engine to compare.
To my untrained eye that just looked like an excessive amount of fuel coming out of the injectors.
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I thought the same. My wife asked if maybe it’s getting too much fuel pressure. I’m ordering the actron tbi fuel pressure tester this morning. Never gonna hurt to have the proper tools and spare parts on hand.
__________________
Scott
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01-11-2019, 06:18 AM
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#62
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Rivet Master
1974 20' Argosy 20
Richmond
, Kentucky
Join Date: Jan 2003
Posts: 9,115
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Quote:
Originally Posted by Air345Fly
Your video sure sounds like the accelerator pump failing in a
carburator of that era. When the pump didn't work the engine would
stall if you stabbed the gas pedal. But if you accelerated slowly
the engine would run OK.
Since you have a TBI system you probably don't have an accelerator
pump. Is that true? If you accelerate the engine slowly can you
get it to run fast? If so, then your problem must be that you don't
get that extra shot of gas that the engine needs to accelerate.
In a TBI system how does the computer know when to give the
extra shot of gas? Is there a manifold vacuum sensor that
connects to the computer? Is there a temperature sensor that
connects to the computer?
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MAP sensor (manifold air pressure) and TPS (throttle position sensor) along with engine RPM work together to determine how much fuel should be injected.
There is also a temperature sensor that helps the computer to determine the correct mixture.
It will be interesting to see what happens when he slowly pushes on the throttle.
One other possibility I can think of is if work has been done to the injectors at some point, were the correct ones installed? Just a thought.
Brad
__________________
Air forums # 1674
1974 20' Argosy Motor Home
1975 24' Argosy Motor Home
1974 31' Excella trailer (parting out, as of 4/1/2015 I have wheels & windows left to sell)
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01-11-2019, 07:52 AM
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#63
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Rivet Master
1991 25' Airstream 250
Oxford
, Oxfordshire
Join Date: Jun 2007
Posts: 1,253
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01-11-2019, 07:56 AM
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#64
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Rivet Master
1991 25' Airstream 250
Oxford
, Oxfordshire
Join Date: Jun 2007
Posts: 1,253
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My money is still on the throttle body and/or one of the associated sensors.
Is it possible that a partially clogged catalytic converter would also cause those symptoms. Mine has a CC, but not sure whether there were standard outside of California or indeed whether your coach has one.
Quote:
Originally Posted by bkahler
MAP sensor (manifold air pressure) and TPS (throttle position sensor) along with engine RPM work together to determine how much fuel should be injected.
There is also a temperature sensor that helps the computer to determine the correct mixture.
It will be interesting to see what happens when he slowly pushes on the throttle.
One other possibility I can think of is if work has been done to the injectors at some point, were the correct ones installed? Just a thought.
Brad
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01-11-2019, 11:31 AM
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#65
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Rivet Master
1984 31' Airstream310
Honokaa
, Hawaii
Join Date: Jun 2010
Posts: 993
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How's this for a long shot: the coach is nearly 30 years old and is reported to have very low mileage. Any chance that it has the original set of spark plugs? Might be worth pulling #8 just to take a look.
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01-11-2019, 12:34 PM
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#66
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3 Rivet Member
1986 32.5' Airstream 325
Merritt Island
, Florida
Join Date: Nov 2018
Posts: 122
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I will pull a couple plugs to check....
Got it timed today - 4 degrees btdc.
Put in tps -
Results the same .... The IAC is next - napa should have it within the next couple hours - there are two possible choices (12mm or 14mm)- only one avail locally so hoping its the right one - I have mine out to match it up.
I also bought an o2 sensor. Have not installed that yet.
The catalytic converter is also something I have considered - I may disconnect it to see if it has an effect. Its just behind the muffler on this motorhome.
As to slowly increasing rpm - I can get it to a higher rpm that way but it still eventually bogs down (under no load) - In drive (under load) I cant get it much above 2000-2500 rpm
I am learning alot about this motorhome which is good.
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01-11-2019, 01:23 PM
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#67
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Rivet Master
1991 25' Airstream 250
Oxford
, Oxfordshire
Join Date: Jun 2007
Posts: 1,253
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Quote:
Originally Posted by sraab928
I will pull a couple plugs to check....
Got it timed today - 4 degrees btdc.
Put in tps -
Results the same .... The IAC is next - napa should have it within the next couple hours - there are two possible choices (12mm or 14mm)- only one avail locally so hoping its the right one - I have mine out to match it up.
I also bought an o2 sensor. Have not installed that yet.
The catalytic converter is also something I have considered - I may disconnect it to see if it has an effect. Its just behind the muffler on this motorhome.
As to slowly increasing rpm - I can get it to a higher rpm that way but it still eventually bogs down (under no load) - In drive (under load) I cant get it much above 2000-2500 rpm
I am learning alot about this motorhome which is good.
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Getting the correct parts for the Motorhome chassis is not always as straightforward as one might hope. I spent days (as did Martin and Brad) trying to sort out a fault code on my coach caused by an incorrect knock sensor. One thing I have found useful is the AC Delco parts look up by VIN, which is here:
https://parts-catalog.acdelco.com/ca...log_search.php
I usually cross ref with RockAuto to try and get a clear picture on which is the correct application for my 250.
TBI UNIT MODEL 220 6C1-1 - detailed stuff/parts etc in this section of the Light Truck Unit repair manual, link below
The GM parts wiki goes into even greater detail where you can see blow outs for parts catalogues in different months. A lifetime's work...and worth checking out if you get really stuck for parts
http://www.gmpartswiki.com/query
It works well in concert with the unit repair manual, garage manuals etc
1991_Chevrolet_Light_Truck_Service_Manual
http://www.73-87chevytrucks.com/tech...ice_Manual.pdf
Light_Truck_Unit Repair manual 1991
http://www.73-87chevytrucks.com/tech...air_Manual.pdf
Fuel, Emissions and Driveability 1991
http://www.73-87chevytrucks.com/tech...iveability.pdf
Wiring manual 1991
http://www.73-87chevytrucks.com/tech...ing_Manual.pdf
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01-11-2019, 03:08 PM
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#68
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3 Rivet Member
1986 32.5' Airstream 325
Merritt Island
, Florida
Join Date: Nov 2018
Posts: 122
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Quote:
Originally Posted by Boom Sounds
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Thank you for the detailed reply. The part at Napa was not correct. We did use the vin number and rock auto as a reference. Hopefully the correct one will be there in the morning.
__________________
Scott
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01-11-2019, 04:00 PM
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#69
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Rivet Master
1991 25' Airstream 250
Oxford
, Oxfordshire
Join Date: Jun 2007
Posts: 1,253
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Quote:
Originally Posted by sraab928
Thank you for the detailed reply. The part at Napa was not correct. We did use the vin number and rock auto as a reference. Hopefully the correct one will be there in the morning.
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What a pain. I put more trust in that AC Delco VIN lookup given that they are the 'official' GM parts supplier, but that isn't fool-proof.
Nick
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01-12-2019, 10:22 AM
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#70
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3 Rivet Member
1986 32.5' Airstream 325
Merritt Island
, Florida
Join Date: Nov 2018
Posts: 122
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Well new iac valve installed and same result. She runs great up until about 2000-2500 rpm. If I push the throttle really slow under no load I can get her to 4000 before she bogs down. My next step is to wait for my obd1 setup to come and use tuner pro rt on the laptop to see what’s going on. I have not looked yet but I assume the connector will be under the dash somewhere?
__________________
Scott
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01-12-2019, 01:22 PM
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#71
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Rivet Master
1991 25' Airstream 250
Oxford
, Oxfordshire
Join Date: Jun 2007
Posts: 1,253
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Quote:
Originally Posted by sraab928
Well new iac valve installed and same result. She runs great up until about 2000-2500 rpm. If I push the throttle really slow under no load I can get her to 4000 before she bogs down. My next step is to wait for my obd1 setup to come and use tuner pro rt on the laptop to see what’s going on. I have not looked yet but I assume the connector will be under the dash somewhere?
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Yep, mine is just to the left of the lower part of steering column, kinda tucked away, but if you contort your body, stick your head in the footwell and legs in the air, you'll see it.
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01-12-2019, 04:50 PM
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#72
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Rivet Master
1984 31' Airstream310
Honokaa
, Hawaii
Join Date: Jun 2010
Posts: 993
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One more thing: the inside of your distributor does not look familiar to me. Is it an HEI distributor with the ignition coil inside the distributor? If you did not get a new coil with the distributor, replacing the coil is my next guess. Either way, it’s cheap PM.
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01-12-2019, 05:23 PM
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#73
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Dazed and Confused
Currently Looking...
1983 31' Airstream310
Hillsburgh
, Ontario
Join Date: Sep 2012
Posts: 3,805
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New plug wires, sparkplugs, OBDII readers, IAC valves, MAP sensors, O2 sensors, ICM, pick-up coil, coil trigger, fuel filter, fuel pump, new distributor, rebuilding carburetor accelerator pump, TPS sensor; and it's still not working right......
You still haven't found the infamous leaking exhaust manifold beside the starter yet.
When my guy makes up motor mounts to mount my Cummins in the P30 chassis, do you want me to get him to make another set at the same time for you?
Still wishing you success.
Sidekick Tony
__________________
Per Mare, Per Terram and may all your campaigns be successful.
“It’s a recession when your neighbor loses his job; it’s a depression when you lose your own.” "Harry S Truman"
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01-12-2019, 06:23 PM
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#74
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3 Rivet Member
1986 32.5' Airstream 325
Merritt Island
, Florida
Join Date: Nov 2018
Posts: 122
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Quote:
Originally Posted by Isuzusweet
New plug wires, sparkplugs, OBDII readers, IAC valves, MAP sensors, O2 sensors, ICM, pick-up coil, coil trigger, fuel filter, fuel pump, new distributor, rebuilding carburetor accelerator pump, TPS sensor; and it's still not working right......
You still haven't found the infamous leaking exhaust manifold beside the starter yet.
When my guy makes up motor mounts to mount my Cummins in the P30 chassis, do you want me to get him to make another set at the same time for you?
Still wishing you success.
Sidekick Tony
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No new plugs or plug wires yet -
What has happened so far...
New Fuel Pump and Filter - (Installed before I purchased)
New Distributor including cap and rotor - (the was to replace the pickup coil and ICM) - Timed 4 degrees before TDC using plug 5 and bottom indicator.
New IAC
New MAP
New TPS
I have the o2 sensor but have not installed it yet - Just got my cable for the OBD1 and Tunerpro RT software - hoping to hook that up early this week and see if it tells me anything.
My next step after that would be to pull a couple plugs and look - then consider dropping the catalytic converted. I also ordered the Fuel Pressure tester with the fitting needed for me to test the fuel pressure myself (relying on the what the shop I had it at for that info so far - they said 13psi)
To answer the other question above - the coil is separate from the distributor and has not been replaced as of yet. I am getting a nice collection of spare parts....lol I am not discouraged..... My wife has already mentioned a new motor - but honestly I think this motor is gonna be a strong runner when I get it sorted.
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01-14-2019, 01:00 AM
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#75
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Rivet Master
1991 25' Airstream 250
Oxford
, Oxfordshire
Join Date: Jun 2007
Posts: 1,253
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Quote:
Originally Posted by sraab928
No new plugs or plug wires yet -
What has happened so far...
New Fuel Pump and Filter - (Installed before I purchased)
New Distributor including cap and rotor - (the was to replace the pickup coil and ICM) - Timed 4 degrees before TDC using plug 5 and bottom indicator.
New IAC
New MAP
New TPS
I have the o2 sensor but have not installed it yet - Just got my cable for the OBD1 and Tunerpro RT software - hoping to hook that up early this week and see if it tells me anything.
My next step after that would be to pull a couple plugs and look - then consider dropping the catalytic converted. I also ordered the Fuel Pressure tester with the fitting needed for me to test the fuel pressure myself (relying on the what the shop I had it at for that info so far - they said 13psi)
To answer the other question above - the coil is separate from the distributor and has not been replaced as of yet. I am getting a nice collection of spare parts....lol I am not discouraged..... My wife has already mentioned a new motor - but honestly I think this motor is gonna be a strong runner when I get it sorted.
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I have no doubt you'll sort this soon and suspect it will be a cheap fix (aside from your time). You'll also have a pile of spare parts which might just get you out of trouble one day. Also, worth putting vacuum leaks around the throttle body/hoses on your list as you work through it.
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01-14-2019, 06:03 AM
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#76
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3 Rivet Member
1986 32.5' Airstream 325
Merritt Island
, Florida
Join Date: Nov 2018
Posts: 122
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There are no vacuum leaks in the engine area. I have also vacuum tested the ports individually to see if ones clogged. The only thing I haven’t checked in the line that I assume runs all the way to the gauge on the dash. I get around 15” at idle at the gauge in the dash.
__________________
Scott
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01-14-2019, 06:19 AM
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#77
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Rivet Master
1974 20' Argosy 20
Richmond
, Kentucky
Join Date: Jan 2003
Posts: 9,115
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Since you've not mentioned it (or at least I don't think you have), does the exhaust appear to be rich? In other words as you start to accelerate does the exhaust start turning black or does it smell rich?
__________________
Air forums # 1674
1974 20' Argosy Motor Home
1975 24' Argosy Motor Home
1974 31' Excella trailer (parting out, as of 4/1/2015 I have wheels & windows left to sell)
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01-14-2019, 08:00 AM
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#78
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3 Rivet Member
1986 32.5' Airstream 325
Merritt Island
, Florida
Join Date: Nov 2018
Posts: 122
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Quote:
Originally Posted by bkahler
Since you've not mentioned it (or at least I don't think you have), does the exhaust appear to be rich? In other words as you start to accelerate does the exhaust start turning black or does it smell rich?
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No smoke of any kind at anytime. It does smell like typical 90’s exhaust. Lol.
__________________
Scott
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01-14-2019, 09:58 AM
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#79
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Rivet Master
1991 25' Airstream 250
Oxford
, Oxfordshire
Join Date: Jun 2007
Posts: 1,253
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Quote:
Originally Posted by sraab928
There are no vacuum leaks in the engine area. I have also vacuum tested the ports individually to see if ones clogged. The only thing I haven’t checked in the line that I assume runs all the way to the gauge on the dash. I get around 15” at idle at the gauge in the dash.
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including all the gaskets on the Rochester 220 and the small hard plastic hose in front of the throttle body.
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01-14-2019, 10:12 AM
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#80
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Rivet Master
1992 36' Land Yacht
Grayson
, Georgia
Join Date: Nov 2011
Posts: 1,719
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I'l be watching this thread very closely. I currently have a 1991 AS Land Yacht with a 454 TBI engine. Recently I had a very bad incident that caused a no start issue. After having a very close by lightening strike occur at the house (MH was plugged in) I found that the MH wouldn't start reliably. It started fine originally but wouldn't rev up. After a few starts it wouldn't start at all. Ended up having it towed to a near by truck repair center. They were able to diagnose it to a bad ECU. The power surge also fried my distributor model and the DRAC unit. After more money than I would like to say, they did replace the ECU and found it was damaged and the cause of most of my problems. The ECU was pricey and there was no reliable way to verify it was the cause of the problem. No codes were found. The did find a loaner that they swapped in and that allowed it to restart. Have had no issues with it since.
Good luck on yours. I have family that lives on Merritt Island so I'm familiar with the area. The Bridge over the Banana River is a bit steep so I can see your concern.
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