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no power
https://slantsix.org/forum/viewtopic.php?t=49174		 Page 1 of 2
Author:  lance [ Sun Jul 01, 2012 8:43 pm ]
Post subject:  no power
i have 87 225 ca. ram150 w/120k miles on it. usually it gets up to 50 or 55mph then starts backing down with a shuddering feel. does same thing on hills but of course at slower speed. it runs fine around town when you take it easy. i've checked stuff like fuel filter, and fuel pump. is this motor just tired or is it something specific like bad cats, def computer carb assist distributer advance. its getting worst.
Author:  SlantSixDan [ Sun Jul 01, 2012 10:57 pm ]
Post subject: 
Sounds like it could be transmission trouble -- can't tell from your description if it's the vehicle that jerks and shudders and slows down (but the engine runs OK) or if it's the engine itself that sputters and wants to cut out at speed.
Author:  Slanted Opinion [ Mon Jul 02, 2012 3:50 am ]
Post subject: 
When it starts shuddering and slowing down, shift into neutral and see if the engine will rev quickly and strongly.

If it will, you may be looking at transmission issues.

If it sputters and gasps, then your problem is likely fuel or ignition.

- Mac
Author:  lance [ Mon Jul 02, 2012 6:32 am ]
Post subject: 
Thanks for your responses! the truck is a 4 speed. I'll venture onto the freeway this morning when i go to work and try to determine if the trouble is motor or trans.
Author:  DadTruck [ Mon Jul 02, 2012 10:38 am ]
Post subject: 
My 83 D-150 would do that ay highway speeds and a full fuel tank,,
engine would shutter, with some violent shaking then recover, would do it less and less as the tank moved off full,, from 7/8 full to empty, no issues.
,, found that the gas tank vent line to the charcoal canister was blocked,,
Author:  tyb525 [ Mon Jul 02, 2012 1:47 pm ]
Post subject: 
My D-100 would do that on rainy days before I changed the spark plugs. The old ones were allowing moisture in and causing one or two plugs to not fire.
Author:  lance [ Wed Jul 25, 2012 7:02 pm ]
Post subject: 
no power update 2. after running my d150 on the freeway, i feel the the lack of power to be an engine problem and not the transmission. i took one of you guys advise and disconnected the line from the gas tank to the charcoal canister and the truck appeared to go a bit faster, but still no power going up an incline. i was curious to see how much gas would flow out of the gas line from the gas tank after disconnecting it from the filter at the front of the truck. not much gas flowed out. it was like a little shot of gas, then it would stop for an instant, then repeat. is there another filter that could be partially clogged at or in the gas tank. and was this a valid test? your responses eagerly awaited!
Author:  SlantSixDan [ Wed Jul 25, 2012 10:41 pm ]
Post subject: 
Quote:
no power update 2. after running my d150 on the freeway, i feel the the lack of power to be an engine problem and not the transmission. i took one of you guys advise and disconnected the line from the gas tank to the charcoal canister
Put it back. That's not causing your problem, and disconnecting a line like this is not a fix, it's a diagnostic test -- a sketchy one, too.
Quote:
and the truck appeared to go a bit faster
The power of suggestion -- nothing more.
Quote:
i was curious to see how much gas would flow out of the gas line from the gas tank after disconnecting it from the filter at the front of the truck
With the engine running or cranking it with the starter, or?
Quote:
is there another filter that could be partially clogged at or in the gas tank
Yes, there's a strainer on the end of the fuel pickup pipe which is part of the fuel gauge sender.
Author:  lance [ Thu Jul 26, 2012 5:51 pm ]
Post subject: 
The engine was not running, nor was I cranking it with the starter. I had the battery disconnected. Probably a better way to check that strainer at the end of the fuel pickup pipe which is part of the gauge sender?
Author:  SlantSixDan [ Thu Jul 26, 2012 6:59 pm ]
Post subject: 
Quote:
The engine was not running, nor was I cranking it with the starter.
Then all you would expect to come out of the fuel filter is a dribble/trickle. Only when the fuel pump is operating will there be any kind of flow.

Speaking of flow: Your California '87 225 B-van has two(!) catalytic converters and an oxygen sensor. How old are those items? The cats are very likely clogged and restricting exhaust flow, and the O2 sensor, if it's more than about 50k miles old, is overdue.

Keep in mind these final-year slant-6s had next to zero power even in brand new perfect condition. They wheezed out 85 horsepower (less than that in California configuration, maybe 80 if you got a good one). That is grossly insufficient to push a brick like yours through the wind with any kind of hustle at all. Zero to sixty in 45 minutes or so.

A guy near me just picked up an '87 California B150, 225 engine and dealer air conditioning, automatic transmission and 12,000 (12k) original miles. It is in Ziploc-bag condition. His complaint is the same as yours: No power, no fuel economy. Can't get out of its own way, can't pass a gas station. He and I have worked up a list of improvements we're going to be doing. Unless I am a moron, the end result will be much better performance and driveability, a mileage improvement, and still passing emission tests. However, while the emission standards in BC are stringent, they aren't as rigidly enforced as the ones in California (where you MUST have all original equipment and configuration -- correct carburetor, etc. -- or no matter what's coming out the tailpipe, you flunk smog).
Author:  lance [ Thu Jul 26, 2012 9:05 pm ]
Post subject: 
I bought my truck new. I have no delusions of power and speed; but I would like to get back most of its performance. The oxygen sensor has been replaced. So possibly one or two clogged catalytic converters. How does one check those suckers?
Author:  SlantSixDan [ Fri Jul 27, 2012 1:08 pm ]
Post subject: 
Are the catalytic converters original to the truck? If so, they are almost certainly quite past due. Do you have (can you get hold of) a vacuum gauge?
Author:  lance [ Sat Jul 28, 2012 9:30 pm ]
Post subject: 
The catalytic converters are original as is the muffler which has a tail pipe of an inside diameter 1 7/8 ". I dug out my vacuum gage, that I've had for ten years and never used, and connected one end of the hose to the line from the air cleaner housing to the intake manifold, and the other end thru the firewall into the cab and onto the vacuum gage. When I increased the egine speed from idle to 2500 rpm in nuetral, the vacuum increased. According to the little vacuum gage instructions, that indication is good. However while driving under an increasing load the vacuum would drop to near zero. I think you are right, the cats are quite past due. Now I'm considering taking my truck to a muffler shop and let them have at it; or is there a better way?
Author:  SlantSixDan [ Sun Jul 29, 2012 12:27 am ]
Post subject: 
Catalytic converters don't play nicely with carburetors under the best of conditions. 120k miles is not the best of conditions. Sounds like you are due for an exhaust system. You're constrained in the degree to which you can modify the system and still pass smog. Functionally you would be much better off replacing the front reduction converter and aft oxidation converter with a single 3-way converter in the underfloor location, and you can get CARB-certified (California-legal) 3-way converters, but I don't know if a smog tech would look in his book and see that it's supposed to have two converters and flunk you instantly no matter how clean the exhaust coming out the tailpipe. Do some research on that one; the answer you get will likely depend on whom you ask on what day under which phase of the moon. :-(

Assuming you can get away with this mod, the shopping list for your exhaust system looks like this:

Catco #512006 CARB-approved 3-way catalytic converter with air injection tube. I've seen it for as little as $70 and as much as $170. No experience with "Max Auto", the place I found on Google selling it for $70, so no idea if that's a screamin' deal or a counterfeit part or what. Summit has it for $117, see here. Install this converter in the location of the present aft/downstream/underfloor converter. Eliminate the forward/upstream/engine bay converter; the new converter does the job of both old ones. New 2ΒΌ" pipe from just ahead of (removed) forward converter to inlet of new converter (keep existing headpipe flange, which is nicer than commonly made by exhaust shops). Extend the air injection pipe so it connects to the new converter rather than to the exhaust pipe. Wrap the headpipe (from manifold outlet to catalyst input) with thermal insulating wrap, such as this, to get the converter up to temperature in a hurry and keep it there. Voila, clean unrestricted exhaust. Send it through a nice big quiet free-flowing Walker #50051 muffler (do not substitute) and appropriate tailpipe.
Author:  emsvitil [ Sun Jul 29, 2012 1:53 am ]
Post subject: 
A way around the 2 converter problem is to have the 3-way converter up front, and a hollowed out converter in the rear so it looks like you have 2 converters.

You can even make an exhaust resonator out of the rear one by drilling some holes in a section of exhaust pipe and shoving it down the middle of the hollow converter.........
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