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Hey guys, New to the site, GLAD I FOUND IT! I have an 87 W150 318.. My question is the truck runs great when its cold but after it warms up I lose power and it starts backfiring... Any ideas?
 

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440 and a 4 speed
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Hi...

welcome to the forum...


nice truck...


few questions...


what (if anything) has been done to the truck?

Did this just start happening...or did you buy it this way?



Sounds mostly like a vacuum issue that comes into play after the thing warms up.....I'd look closely at the air injection system (if it's still equipped) as the 1st possible problem - remove it if possible - or atleast the belt to the air pump. See if the backfire goes away.
 

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Thanks.. Not much has been done to the truck.. It had a 4bbl on it when I get it, ran so so, didnt seem to have any power with the 4bbl..If you stepped into it, it would bog down.. But thats not why I took it off, had an oil leak, thought it was coming from the back of the intake.. I was wrong.. It was the oil sending unit...
 

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Ok...that helps some.


I suspect it's a vacuum leak somewhere into the manifold - mabe the EGR is at fault - usually there is a vacuum switch on the front of the intake manifold that has 2 or 3 vacuum lines running to it - one is usually a supply from the intake - the other is switched on to the vacuum when a certain temp is reached (the switch is in the water jacket of the manifold) - and it might be pulling the EGR valve open and that might be the source.....

If you don't have to deal with emissions - or strict emissions - eliminate all the vacuum lines that you can - also check to see if the passenger side exhaust manifold's cold block off is functioning....or bypassed. There is a little flapper valve that opens and closes at the base of the manifold - when cold it diverts the exhaust flow through the intake manifold to the other side and out.... I think it's useless - and I usually permanently fix the valve open and block off the exhaust ports from the heads to the intake when the intake manifold is off.

If you have light emission checks - you can put 3-5 ounces of Acetone per gallon of gas a few days before the check and the emissions are next to nothing.

The air pump system could be failed too - (broken line) - again remove all that if you can - you really dont need it.

I might think of some more ideas later...
 

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also

there is a bunch of vacuum crap that goes from the intake to the passenger side fender - and has some electrical stuff attached to it and then some of it goes to the prevously mentioned passenger side cold block off on the exhaust manifold. you can eliminate all this and even unplug the electrical stuff it's attached to - just make sure the vacuum lines are plugged at the intake manifold openings.

The only vacuum lines I run are the ones to the power brake booster, the PCV valve, and the HVAC control system - all other ones have been eliminated and the truck runs great. (you might have one from the base of the carb to the choke on the carb...depending upon carb and another one from the carb to a charcoal canister).
 

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Thanks Delray I'll give that a try.. Might have to wait till its a little warmer! Its 7 outside rite now! Plus about 6 inches of snow! And I don't have to deal with emissions, I live In Ind..... Again, Thanks! Robert
 

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could be either the valve on the air pump being bad or a coil or distributor pickup flaking out as the motor heats up; been there done that mess.
 

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RobRoy,

Welcome to DodgeTalk.

As to your problem: check to see that the secondary air valve of your four-barrel carb has not been removed or otherwise disabled. If it does not have one, then it should.

Jeff
 

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Discussion Starter #9
Fins, I should have said that the 4bbl is no longer on the truck.. I put the 2bbl carb and intake back. But thanks for the info.. Well take all I can get!
 

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Mopar Madness - Get it...
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Thanks Delray I'll give that a try.. Might have to wait till its a little warmer! Its 7 outside rite now! Plus about 6 inches of snow! And I don't have to deal with emissions, I live In Ind..... Again, Thanks! Robert
7 degrees and only 6" of snow? Damn Rob, that's tee-shirt and shorts weather here... :D :D :D

(And welcome to The Big Boys Club... :crazy: )
 

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Thanks bherder! I just hate the cold! You can have all this cold weather! LMAO!!This is a GREAT SITE! This makes my Fifth Dodge truck... Had an 80 D100,Handed down from dad..had to put it down had 275k on it and the body was gone.. 87 W150 slant 6 4 spd,tree fell on it, loved that one! 97 1500 ss/t, another great truck! But the family was getting to big for single cab.. Now I have 06 1500 4x4 sport quad cab. And another 87
 

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440 and a 4 speed
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I just hate the cold! You can have all this cold weather!

I hear ya...

lets see...we are having our winter day or two here in South Florida....Its in the low 70's high 60's today and we are supposed to get a front through here to put is in the bone chilly 40's tonight....and damn thats too cold for me!!!!

I was thinking I was gonna turn a wrench or two on my friend's 74 Fury tonight...but I think I'll wait till this weekend when it's warmed back up...it aint going nowhere till I put the distributor back in and wire it up....
 

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A TREE fell on it????
What are the chances of that happening?????
Should have bought a Lotto ticket, with THAT string of "LUCK"

Long story... One to many beers and a chainsaw, and letting my buddy talk me into helpin him cut a tree down!
 

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440 and a 4 speed
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Long story... One to many beers and a chainsaw, and letting my buddy talk me into helpin him cut a tree down!

To quote Homer Simpson..... D'oooooh!!!!


I can relate...
 

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Mopar Madness - Get it...
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(GAWD ... 80 degrees ... I'd be DYING ....)

Yeah, well, just remember.... While you're sitting there on 'Palm Tree Beach' sipping a margarita out of a hollowed-out coconut shell with a little umbrella stuck in it, it's us die-hard Northerners that keep the Hottintotts from completely overrunning the 'warm-climate' states from the north....

We drink whiskey. And lot's of it.
All whiskey can be sent to:

Bruce Herder
P.O. Box 286
Usk, WA. 99180

:D :D :D :D

(Send some to Ed too .... His wife says he needs to get away from valve covers and get under the blankets to keep her warm...)
 

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Do you have any Ideas about my first post bherder?
Mmmmmm ..... Dunno Rob... There are just too many 'variables' here. As in, don't know what kind of shape the engine/carb/ignition/ etc is in.... It's one of those 'gotta BE there' kinda' things....

Being as you changed out the intake, WE, as in being on the other end of a keyboard, don't really know if it's all buttoned up perfect or not ....
It could be carburation, it could be ignition, could be as others have said, a vacuum leak....

I would suggest getting a vacuum gage and see what that says.... A vacuum gauge will tell you a LOT.....
 
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