Ok here's the deal. Once you get past 3/4 throttle on my 83 D150 its bog city, I mean nothing, it actually loses power. I've done the basics: tune up, replaced some vacuum hoses, replaced carb base gasket, reset the timing to factory specs......Ideas?

I'm starting to lean towards Cat converter. Lots of water vapor out the tailpipe and very odd smell, not like rotten eggs, but sweet sickly. Truck doesn't burn any oil, or lose any coolant so I don't think its a head gasket or anything like that. It does have ESA (leanburn) but that seems to be operating normally (if there ever was such a thing). Also it has a reman Holley 2bbl carb on it that doesn't look that old (remaned by Holley too, so one would think it was done correctly), so I'm kinda ruling out the carb, but not completely (yet). Suggestions??

If your catalytic converter is original it probably is restricted. Mine was clogged on my d150. It really slowed the truck down. When I took it off you couldn't see light through it. I had to pass an emissions inspection so I installed a larger catalytic converter from a ford 300 six. If you just have to pass a visual emissions test I would just hollow out the inside and put it back on.
Other things to check are the accelerator pump and power valve adjustment , if there is one. Another thing to check is your timing chain slack(wear). Good luck !
D150

If you don't have to pass emissions tests at all get rid of the cat and leanburn all together

Acellerator pump works fine, and I dont think there are any adjustments besides idle mixture, so thats why I'm headed towards the cat. I don't think its original, but its possible. Truck only has 70k on it, so maybe. I don't have to pass an emissions test, but all emisions components have to be present for a visual inspection. This means I've gotta put an airpump back on it too. Thats long gone, but I figure with a working one on there it will help the new cat......
I don't think it would be timing chain slack, the timing advances steady, not erratic, nothing backfires, so I don't think it could be that. It has good power up to 3/4 throttle, then it goes flat.

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"That thing gotta HEMI in it??"

ugh--leanburn. I feel..or have felt, rather, your pain. Which vacuum lines have you replaced. if you have not replaced the ones going to the computer, those are the most important...so make sure those hoses are good. Second, check the two pickup gaps in the distributor, if you havent replaced the cap and rotor, refresh those.

On the cat, one thing i have noticed on virtually all catalytic converters that are headed south..the exhaust begins to have a distinct "gurgle" to it. Another way to check is to have someone spike the throttle while you have you hand in front of the tail pipe (not TOO close!!) If you detect anything more than a minimal delay between the rev and increased exhaust pressure out of the pipe, something in the exhaust system is restricting flow--quite possibly the cat. However another possible culprit (sp) could be the flapper valve in the exhaust manifold. Check to see that this turns freely (after the manifold has cooled off)

If the problem turns out to be the cat....dont just slap a new one on w/o the air pump. W/O the "fresh" air from the air pump the cat(s) on these trucks will melt themselves down quickly and you will be right back where you started (ask how i know )

Personally, if all i had to pass was visual, i would just remove the cat, knock the platinum covered honeycomb out, and re-install the empty cat (as was already suggested). If you keep your slant in good tune you should not have any problems getting passed the "sniffer" w/o a cat.

Good luck

-S/6

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The "Silver Bullet"
87 Ram D150

Well, I've replaced all the vacuum lines, replaced the carb base gasket, already did a complete tune (including cap, rotor, wires), reset the timing....it was 14 degrees retarded, checked the air gaps wen I was replacing the cap and rotor, checked the heat riser....it works fine. So there's where I'm at.

I don't know about a gurgling noise, but there is a lot of vapor coming out the tailpipe, but not much for strong exhaust flow. Sounds restricted, so I bet its what my problem is.....plus the smell!!!! Absolutely horrible.
Sounds like I'm gonna do a complete exhaust, an air pump, and a recheck after that. Gotta get the performance back, its just horrible on the highway.

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"That thing gotta HEMI in it??"

I re-read your first post--this "sweet-sickly" exhaust smell has me wondering if you are burning a little antifreeze (not necessarily a blown head gasket, but it may be leaking enough into the combustion chamber to produce the "sweet" smell) Have you done a compression check? Id do this first before i cut the cat off...of course if it has been burning antifreeze the cat is probably shot anyway

BTW--another way to check the cat flow is to drill a small hole (1/4" +/-) just before and right after the cat. Exhaust escaping both holes should feel about the same, if the one before the cat is flowing much more pressure than the hole behind you have a plugged cat. (these holes can be easily tack-welded shut)

-S/6

wow, does this sound the same...

the most performance i got was with a BBD on a supersix intake and a free flowing exhaust, other than that, get a 4bbl, do some headwork, and get headers or Dutra Duals...

Justin

Ummmmm..........no it doesn't

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"That thing gotta HEMI in it??"

no it doesnt what? Burn antifreeze? Sound the same? Have compression?

ohh, i meant to say that it sounds the same as my "first" posts ever

i went through the same crap, and it took me awhile of tinkering to figure out what was wrong, i went to a supersix with a bbd, it helped a bit, then i scrapped the lean-burn, that helped alot, then did a WHOLE lot of other, small, non expensive stuff before she woke up as much as it would

now i'm shooting for 15's in a truck, actually, i may try 14's but no lower

Justin

Oh, I meant no it doesn't sound the same as my problem that I posted, in reference to the previous post about modifying.......sorry for the confusion

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"That thing gotta HEMI in it??"

Well, mine has the factory Holley 2bbl on it, so that would make it a super 6 already, right? Now about trashing the leanburn........are you saying your's bogged after 3/4 throttle before trashing the leanburn? Did you have anything else that contributed to the bog besides the leanburn? I'm just looking to get it respectable in performance, not ultimate for speed. If I wanted to do that, I'd sell my kids, wife, house, etc and buy a HEMI crate motor to swap in.......

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"That thing gotta HEMI in it??"

A manifold vacuum gage could diagnose a clogged catalytic converter. If the converter is clogged real bad your vacuum reading won't jump as high when you decelerate and be lower than normal at idle. If it were my vehicle I would splice in section of pipe where the converter is and road test it. If its not your converter just splice it back in. My method of splicing is to get a piece of pipe with the same inside diameter as the outside diameter of your exhaust and some muffler clamps.
At what speed do you get the "bog" or hesitation and is it already in drive(if automatic)? If your kick down rod isn't adjusted right it might be up shifting to early. Hope this helps.
Good luck
D150

hey,

Well mine was horrible with the lean burn for after 3/4 throttle, After swapping the old style ignition, and cutting out the cat and getting a free flowing muffle my MPG went up and the power/drivability increased noticably.

Justin