Sluggish acceleration when warm - DodgeTalk : Dodge Car Forums, Dodge Truck Forums and Ram Forums
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#1 Old 10-30-2012, 10:48 AM
jbaum75
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Sluggish acceleration when warm

Looking for some knowledge. Got a '76 W-200 318 2 bl that has sluggish acceleration only when engine has warmed to operating temp. When the engine is cold or warming it runs great! It seems to only be an issue at low RPM. If I ease into the gas it will accelerate fine but under load (when I am towing or accelerating "quickly") the engine is choppy with no power??? Carb rebuilt 9 months ago, cap, rotor, wires, plugs replaced 2 years ago. The truck was running good till about a month ago when this popped up. Wondering if the carb needs some type of adjustment?? I can't understand why is runs like nothing is wrong when the engine is cool??

Any suggestions.
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#2 Old 10-30-2012, 10:54 AM
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Im going to say ignition. A lot of times the "warmed up" issue shows itself because the pick up plate needs to be adjusted. I'd also check your timing and check the choke on the carb.

1987 Dodge W-150 "The Beast"
some sort of lift
33" AT's
LA 360 bored .030 over, EQ Magnum heads, Hooker Headers, true dual exhaust, Holley 4160 w/Truck Avenger parts, Edelbrock Performer dual plane intake, StreetFire ignition box & MSD coil
208 t-case/727A trans w/3.23 gears
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#3 Old 10-30-2012, 12:26 PM
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Choke.

Sounds like it's running great when choked, until it warms up. Make sure the choke is fully disengaged after warm-up, then check for adequate fuel delivery and/or adjust mixture screws...

...or it could be a vacuum leak as well...

1975 Dodge D100
-Clubcab "Adventurer Sport"
-1-ton Dually
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#4 Old 10-30-2012, 09:37 PM
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Thanks for the quick reply's folks!! I Checked the choke after experiencing the sluggishness and it was wide open. My Dodge has the Carter BBD carb, and the Chilton repair manual states that adjusting the the mixing screw does not significantly alter performance......? I will have to do some investigating regarding the potential vacuum leak. The pick-up coil suggestion is intriguing. The drop off in power is most noticed when the truck shifts from 2 to 3. After shifting there is noticeable sluggishness so I would compensate by pressing on the gas, which caused some choppy engine behavior until I press the gas pedal down to the point that the tranny kicks down then rpm's jump up and the sluggish behavior disappears. So it seems to be rpm related. Also, for the entire time I have been driving this truck (~2 years) I have experienced hard starting when the engine is warm which led to the rebuilt carb, which improved performance somewhat but not the hard starting. I am wondering if I should replace the entire distributor? After replacing the pick-up coil and reluctor, it wouldn't be that much more for the whole unit.

I hope my lengthy description makes sense and thanks for sharing any information.
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#5 Old 10-30-2012, 10:08 PM
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Adjust the pick up plate. If that doesn't work, im still going to say its an ignition issue. My truck had similar behavior when I first got it. I threw in a new HEI distributor, coil, plugs, and wires. It ran awesome after that.

1987 Dodge W-150 "The Beast"
some sort of lift
33" AT's
LA 360 bored .030 over, EQ Magnum heads, Hooker Headers, true dual exhaust, Holley 4160 w/Truck Avenger parts, Edelbrock Performer dual plane intake, StreetFire ignition box & MSD coil
208 t-case/727A trans w/3.23 gears
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#6 Old 10-31-2012, 08:00 AM
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My two cents would be to look for a vacuum leak, especially since it runs ok when choked. That includes checking the carb mounting bolts, and the vac advance diaphram on the distributor. Also REMOVE and check all the vacuum lines, on a 76 there aren't that many, and they always develop leaks underneath where you cant see them for some reason.

1974 Dodge D100 318 4-spd

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#7 Old 10-31-2012, 09:57 AM
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usnavyvet, that is a pretty good suggestion. if its running fine with the choke on (pulling air from the leak) and not with the choke open (pulling air from the carb and the leak), the engine would be running lean and not getting enough gas. that goes with what he said about the high rpms. more rpms, more gas, runs better.

1987 Dodge W-150 "The Beast"
some sort of lift
33" AT's
LA 360 bored .030 over, EQ Magnum heads, Hooker Headers, true dual exhaust, Holley 4160 w/Truck Avenger parts, Edelbrock Performer dual plane intake, StreetFire ignition box & MSD coil
208 t-case/727A trans w/3.23 gears
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#8 Old 10-31-2012, 03:45 PM
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checked the hoses (only three) and they all looked good. How would I test for leaks in the vacuum control? I will adjust the pick-up coil next and see what happens. Also, how much circular play should there be in the distributor? I was looking inside the dist. to check on the condition of components and noticed that the rotor would move back and forth ~1/8 of a turn. Is this normal??

Last edited by jbaum75; 10-31-2012 at 04:05 PM.
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#9 Old 10-31-2012, 03:55 PM
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Best way to check for vacuum leaks is to hook up a vacuum gauge. If I recall correctly you should be get like 12+ on the gauge.

1987 Dodge W-150 "The Beast"
some sort of lift
33" AT's
LA 360 bored .030 over, EQ Magnum heads, Hooker Headers, true dual exhaust, Holley 4160 w/Truck Avenger parts, Edelbrock Performer dual plane intake, StreetFire ignition box & MSD coil
208 t-case/727A trans w/3.23 gears
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#10 Old 10-31-2012, 04:21 PM
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Quote:
Originally Posted by maachine View Post
Best way to check for vacuum leaks is to hook up a vacuum gauge. If I recall correctly you should be get like 12+ on the gauge.
I don't think I completely agree with this. A small leak in a vacuum line or diaphram wont make that much difference on the gauge, but will still affect the carburetor significantly. at least it did on my truck. I think the best way is to unplug and cap at the carb for everything except the vacuum advance, and you can verify the diaphram on the distributor with a vacuum pump. you can also check the dist advance action with the vac pump.

The three hoses to the carb are, I'll guess, the dist vac advance, the pcv valve, and the egr valve. No power brake booster? Anyway you can remove all but the dist adv line and cap the carb inputs. Then see if it runs ok when hot.

1974 Dodge D100 318 4-spd


Last edited by usnavyvet; 10-31-2012 at 04:35 PM.
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#11 Old 10-31-2012, 07:43 PM
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I think the easiest way to check for vacuum leaks is to spray starting fluid (ether) around the suspected areas and wait for an increase in idle RPM's. It works really well around the base of the carb...

1975 Dodge D100
-Clubcab "Adventurer Sport"
-1-ton Dually
-440
-Auto
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#12 Old 10-31-2012, 08:14 PM
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I was looking forward to trying some of the suggestions but the truck died on me this evening and wouldn't start. I am planning on replacing the entire dist. and hope that resolves the problems. I will post back with an update.

in reply to the most recent post, the three vac lines are the pcv, vac advance assist and choke vac assist. brake booster is hooked direct to the intake manifold and I don't think there is a EGR valve??

This dodge is an old military truck that was passed on to the national forest service in southern Illinois then passed on to IL dept of nat resources then to me. Who knows what type of mods have been done to this truck. But, I like it regardless.
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#13 Old 10-31-2012, 08:33 PM
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vaccum should be near 20 on a vac gauge and steady. you can check the dist can by sucking the hose connected to the can with the cap off and see if the plate moves. usually with a vac leak the motor will idle ok but cough and be powerless when the gas is applied. check your timing while under the hood

you like your truck more than you like me. sometimes i do

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#14 Old 11-01-2012, 09:50 AM
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Quote:
Originally Posted by roadram360 View Post
vaccum should be near 20 on a vac gauge and steady. you can check the dist can by sucking the hose connected to the can with the cap off and see if the plate moves. usually with a vac leak the motor will idle ok but cough and be powerless when the gas is applied. check your timing while under the hood
I've found it to be the other way around with a vacuum leak: the motor will have power when gas is applied, but will idle terribly.


1975 Dodge D100
-Clubcab "Adventurer Sport"
-1-ton Dually
-440
-Auto
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#15 Old 11-05-2012, 06:11 PM
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well my duster idled normally but had no power to move

you like your truck more than you like me. sometimes i do

1978 d-150, 95 360, eddy 750, 4 speed auto, 9.25 rear. her name is sabrina

GOD BLESS AMERICA

http://s745.photobucket.com/albums/x...am360/sabrina/
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#16 Old 11-05-2012, 10:02 PM
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Originally Posted by roadram360 View Post
well my duster idled normally but had no power to move
I suppose it would depend where the leak was and whether the engine was warm or cold, also...

1975 Dodge D100
-Clubcab "Adventurer Sport"
-1-ton Dually
-440
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#17 Old 11-07-2012, 06:07 PM
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OK, I got the distributor installed and engine runs good. I want to check the timing but I cant find the timing marks and the repair manual doesn't offer any description of the location. Where are the timing marks on the 318 5.2L? I haven't driven it yet to see if the original problem has been fixed. As soon as I check the timing I will give it a test drive.
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#18 Old 11-07-2012, 06:36 PM
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I have timing tape on my harmonic balancer but thats it right there. Solid line on the balancer will line up with the numbers that were cast on the timing chain cover. If you are looking at the crank pulley from the front of the engine, the numbers are on the upper right hand side.
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1987 Dodge W-150 "The Beast"
some sort of lift
33" AT's
LA 360 bored .030 over, EQ Magnum heads, Hooker Headers, true dual exhaust, Holley 4160 w/Truck Avenger parts, Edelbrock Performer dual plane intake, StreetFire ignition box & MSD coil
208 t-case/727A trans w/3.23 gears
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#19 Old 11-27-2012, 11:34 AM
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It was the ignition control module. the dist. helped but didn't fix. I basically replaced the entire ignition system.

thanks to all for help on this one!!!
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#20 Old 11-28-2012, 06:53 PM
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Another question. When I was adjusting the timing I discovered that the timing was WAY off. If I had to estimate I would say it was set at ~20-25 BTDC (The timing marks only go to 10 BTDC - 10 ATDC, like pic above). Repair manual states that it should be between TDC and 2 ATDC. BUT the engine was running very well after replacing the ICM (before I adjusted timing). So I set the timing as stated in the manual and it runs very differently. At idle speeds it's fine but if I accelerate quickly there is a dramatic loss of power and the engine almost stalls. If I accelerate very gradually the engine runs decent?? What does this mean??

Thanks for all the help in the past. This forum is awesome!
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