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  #1  
Old 03-03-2003, 09:02 PM
johndarling johndarling is offline
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Unhappy Engine struggle at hwy speeds

Any help on this would be great.

87 Chyrsler 5th 110,000 miles. 318 converted from lean burn to mopar electronic ignition and 76 carter non feed back carb the rest of the car is stock. New Fuel pump, filter, PCV, plugs, wires, cap, rotor. Carb set at max vacuum at idle and ingition set at 38* total advance at 3500 RPM thats about 10* at idle.

Symptom:
Runs great at low speed and at hwy speed for anywhere from 45 to 60 min then it starts struggling/cutting out and I can't keep it over 45 mph. Pull over to the side of the hwy and it will idle as long as you want it to. Take off again and can't get up to 45 mph but turn it off for 5 - 10 min and it will be fine at hwy speed for 20 - 30 min then the same sh-t.

Additional info: Lots of blowby coming out of the dip stick tube and valve cover breather. Temp gauge goes up about 10% when the struggling starts.

Possable causes
Coil (original) ?
Plugged Cat. (original) ?

What do you guys and gals think?

Thanks
John
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  #2  
Old 03-03-2003, 10:47 PM
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92whitedak 92whitedak is offline
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I would venture a guess that if it was a plugged cat, you'd notice the problem much sooner. I only say this becuase of the duration you said you allowed the engine to cool and try it again. After running at highway speeds for that amount of time, then 5-10 minutes of cooling, thats not enough to allow the cat to run back down to non-operational temperature. So I don't think it it the cat. Have you noticed a small rattling coming from your engine?


I'm no professional fuel management engineer (cough cough someone-on-here) but I'm going to take a stab and say you've got either a bad fuel pump check valve, a dying fuel pump motor, or a thrown fuel regulator. With a bad motor, its basically due to the fact that the gear drive just can't keep up with the high pressures and you'll die out. You should also hear a pretty whicked sound accompanying this. Have you got a vacuum/boost guage and a fuel pressure guage? Try running both of these while driving. For every increased inch of mercury of vacuum, you should see "about" .50 psi drop in pressure. But as far as the tell-tale signs go, a bad fuel pump motor doesn't show signs of failure until it is actually warmed up. You are basically saying that you've given it time to warm up. I certainly hope someone can decipher this. One too many again tonight...

-Deacon
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  #3  
Old 03-03-2003, 11:29 PM
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JVMopar JVMopar is offline
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It sounds like a fuel problem to me. I'd say that the carb needs to be rebuilt or has the wrong jetting. Mechanical pumps are pretty reliable no matter who makes it so I wouldn't think it was the pump.

A clogged fuel filter can cause this symptom too.

Try driving down the street in 1st gear and see if it cuts out. You should be able to repeat a fuel or ignition problem in any gear. Sounds like fuel to me though.
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  #4  
Old 03-04-2003, 07:59 AM
johndarling johndarling is offline
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Default I think you guys a right on about the fuel

BTW; This is my daily driver. I drive 90 miles oneway for work so I'm clocking 180 miles a day 5 days a week. the 5th gets 25-28 MPG rate now and this summer I'm dropping in a set of headers and a a500 trans to see what kind of gas milage I can get. I want to see if I can get 32-34 MPG

I didn't notice this before but this morning I got down to about 1/2 tank and it sputtered a little. By the time I got down to 1/4 tank it would hardly run. I limpped it to the gas station and pumped in 5 bucks and it ran great until it got down just below 1/2 tank and it started sputtering again so I stopped and put in another 5 and its running good again. I think the tank has alot of sh-t in it or the fuel is contaminated. If the fuel is contaminated with say water will the water be on top of the fuel or will the fuel be on top of the water? I think that what ever is in the tank is staying at the top when it is full and and when the fuel gets low enough and its been slashing around and mixing with the gas it starts gumming things up.

Now I'm thinking I'll pump the tank empty and then fill it up with just a few gallons and see if it helps if not I'm thinking what ever is in there is solid enough to plug up the sock filter and I'll need to drop the tank.

This sound about right?

Thanks
John
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  #5  
Old 03-04-2003, 09:35 AM
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cuda66273 cuda66273 is offline
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Next time it does that, jump out of the car (stop 1st ) and open the fuel cap....does it go Psssssssttttt....maybe your vent is closed off and the pumps trying to suck a vacuum in the tank.

It's worth a try anyhow......
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  #6  
Old 03-04-2003, 10:28 AM
johndarling johndarling is offline
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Default Good Idea

It's doing it every day now so maybe on the way home before I put more gas in it I'll just leave the cap loose on the way home. If it starts sputtering I'll stop and fill it up. Then I'll try the other two things I listed.

Thanks
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  #7  
Old 03-04-2003, 10:57 AM
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5th_Ave_Sleeper 5th_Ave_Sleeper is offline
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When all else fails...........

If you cant get it straightened out, the next step would be to build a solid cammed, 11:1, tunnel ram haven' dual quad suckin, earth shattering 550Hp 360! then put it in the 5th, like me
I think cuda might have nailed it. leave the gas cap loose for a day. and cut off those THREE cats!
Good luck, keep us posted. I will subscribe to this one.
5th
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  #8  
Old 03-04-2003, 11:25 AM
johndarling johndarling is offline
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Default I know 3 cats WTF

5th

I liked the pics of your 5th. It remined me of my old A body sleeper a few (like 15) years ago. My ass end wasn't quite that high ;-) What kind of van did that come out of? I think I've got a 8 3/4 that will fit out of a b body if you need one. No gears just axle and shafts.

My plans for the 5th are;
1. Fit this damb fuel problem
2. (when it warms up) Built a500 OD trans and I think I'm going to swap in a 8 3/4 with 3:55's.
3. Headers. BTW which ones did you go with and how did they fit?
4. (next winter if the shop is finished) Rebuild my '76 Ram 360 and see if we can scare some ricers.
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  #9  
Old 03-04-2003, 11:41 AM
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bbeckwith bbeckwith is offline
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johndarling,

Have you checked your fuel line going from the tank to the fuel pump? Has it been re-routed near the exhaust anywhere? Also, you wondered if water in the tank would be at the top or the bottom, water would be heavier than fuel so it would be at the bottom of the tank. You mentioned the motor temp was going up also, possibly the carb is percolating the fuel, maybe you could try using a carb spacer between the manifold and the carb to keep the carb a bit cooler.

Good Luck
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  #10  
Old 03-04-2003, 05:55 PM
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5th_Ave_Sleeper 5th_Ave_Sleeper is offline
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parts i used

Johndarling;
The 8 1/4" came out of a full size 77 van. so its like 5" to wide.
I would love to help you clean out your garage in the way of that rear end you have. I have family in Mt Pleasant, MI that would go get it for me. Matter of fact my nephew scored a 86 dippy cop car for me yesterday. so i need to make a run up there anyway
Yeah those three cats are outrageouse arent they? can you say "choke city"?
The headers I have are headmans PN 78050 they fit PERFECTLY!.
Olnly trouble is you have to have them un-attached when putting them in, But they must be fed in at the same time the engine is getting dropped in. There is no installing them with the engine in the car. oh and the center drag link has to be unhooked from both sides, cuz it runs through the driver side primaries
Good luck!
If you want to do some trading on some parts contact me at tnjpriest@hotmail.com
5th A.S.
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  #11  
Old 03-05-2003, 10:16 AM
mtrv8n mtrv8n is offline
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I had exactly the same problem last summer,, was getting worse and worse. I realied, that since it went away after idling a bit, that the fuel bowl was not filling fast enough to keep up with fuel demand at speed.

My solution was to replace the fuel pump, which was not operating properly. I had already checked and replaced the filter, and put in several mods to reduce underhood heat to no effect.

The other things which can cause a low fuel bowl condition are a low bowl height(simple adjustment needed), clogged line or filter, clogged or stuck needle seat, or as you hinted, crap in your tank.

You might try a fuel pressure guage to see just where the porblem is. If you are getting good pressure at the carb feed, then it's the carb that needs work...
Maybe the fuel pump isn't seated against the rod properly, and therefore not really doing anything!
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  #12  
Old 03-05-2003, 01:16 PM
6pakman 6pakman is offline
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90 miles one way to work!!!??? wow dude! id move closer to my job to save money on gas and were and tear on that car!!
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  #13  
Old 03-05-2003, 01:46 PM
rusty duster rusty duster is offline
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john,you said that you noticed the temp would rise before the motor would quit.It seems to me that the engine is going lean before it dies.Also when the tank is low on fuel ,it is much harder for the pump to pull fuel upwards from an empty tank.One other thing I'am guessing about is that even though the pump is new it could still have a bad pressure relief valve when hot. GOOD LUCK with the fix.
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  #14  
Old 03-05-2003, 01:53 PM
rusty duster rusty duster is offline
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john,you said that you noticed the temp would rise before the motor would quit.It seems to me that the engine is going lean before it dies.Also when the tank is low on fuel ,it is much harder for the pump to pull fuel upwards from an empty tank.One other thing I'am guessing about is that even though the pump is new it could still have a bad pressure relief valve when hot. GOOD LUCK with the fix.
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  #15  
Old 03-06-2003, 09:16 AM
johndarling johndarling is offline
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Default Update

On Tuesday I drove home with fuel cap OFF and after driving about 20 min (25 miles) I got down to between 1/4 & 1/2 tank it started sputtering. I stopped and put some gas in and ran OK the rest of the way home 55 min (65 miles). Yesterday I had the day off so I didn't do any hwy driving and it ran fine around town with just over 1/2 tank. This morning I filled the tank to just about 3/4 and it ran great until almost work when it started sputtering (not stalling, just sputtering) and the tank is just a little over the 1/2 mark. Symptom seems to happen at any outside temp.

Also you can't just let the car idle a while then take off again the problem will still be there. If you turn the car off for 5-10 min it will go again for a while but if it is below 1/2 tank it will start happening again very soon.

Here is the list of replaced parts so far (and yes this problem started before the parts were replaced);
New Fuel Pump
New fuel filter
New Plugs, wires, cap & rotor.
Replaced Lean Burn Ignition with a known good stock Mopar electronic ignition (everything except the coil).
Replaced the carter lean burn with a known good carter carb(stole from my dads cuda).

This is what I'm starting to think. There is some kind of solid sediment floating in the gas (rust, dirt, ???) and when the car is running at hwy speed it needs allot of gas and as the sediment gets close enough to the pick up it sucks a little into the sock filter. When enough sediment gets on the sock filter it creates a restriction of fuel. Now if you pull the car over to the side of the road and let it idle the restriction is still there and will not fall off sock because the fuel line is still under vacuum. But if the car is turned off and the fuel line isn't under vacuum the sediment drops off. And maybe putting gas in it gets the gas in the tank swirling around enough to wash the sediment off the sock for a while.

Let me know what you think.
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  #16  
Old 03-06-2003, 10:24 AM
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amxauto-x amxauto-x is offline
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Sounds logical. How much trouble to remove the pickup tube from the tank? Do you have to remove the tank? On my van I didn't, but probably do on your car.

Maybe you could try this. When it stumbles, leave the engine running and go back to the rear end and push the car from side to side to slosh the fuel back and forth to try and wash off the sock. Then drive down the road. Worth a try.
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  #17  
Old 03-06-2003, 11:35 AM
6pakman 6pakman is offline
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lets see, 25 to 28 mpg you say, so we will go 26 mpg into 90 miles, thats about 3 1/2 gallons one way 7 gallons total. how many gallon tank does that car have?
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  #18  
Old 03-07-2003, 08:39 AM
johndarling johndarling is offline
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Default About 18 gallons

maybe a little more....
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  #19  
Old 03-07-2003, 10:04 AM
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5th_Ave_Sleeper 5th_Ave_Sleeper is offline
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Question where you at?

Johndarling,
Which Clark Lake do you live at/ in? I punched it up on mapquest and it gave me about 8 different ones.
5th
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  #20  
Old 03-07-2003, 02:32 PM
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71383bee 71383bee is offline
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Question

Do you still have a vent line? it sounds like a pressure related problem. I know that not having a good vent line can give similar symtoms.
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  #21  
Old 03-07-2003, 06:42 PM
sixpackgut sixpackgut is offline
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i know someone who went through this and it was garbage in the gas tank. the gas tank is easy to take out and cheap to have cleaned. i would check fuel pressure at the carb like was suggested but i think its garbage gettin blockin the fuel pickup.
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  #22  
Old 03-10-2003, 10:28 AM
johndarling johndarling is offline
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Default Running fine

OK I fully convinced it's crap in the tank. As long as I keep it above 1/2 tank it runs good.

5th_Ave_Sleeper,

I live in Clarklake MI zip 49234. Just about 7 miles south of Jackson MI

John
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  #23  
Old 03-10-2003, 10:35 AM
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amxauto-x amxauto-x is offline
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I used to live on Jackson st. In Grand Ledge, Mi. was born in Lansing.
Did you try the shake the car idea?
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  #24  
Old 03-10-2003, 09:26 PM
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5th_Ave_Sleeper 5th_Ave_Sleeper is offline
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Biggrin how bout thet rear housing?

Johndarling,
Shoot man you arent to far from Willow run airport are you?
I work for Doug Kalitta at the jet charter service he owns. except I work at the Morristown, TN hanger. So I can have stuff flown between here and MI for nothing! perks I guess.
So what would you want for the housing? not much I hope. I just did a favor for a fellow Mopar brother, gave him a bunch of smallblock parts in trade for beer. I really needed the space!
I sure would like an 8 3/4" cuz according to desktop dyno this 360 is gonna be pushing around 550HP. I dont think the 8 1/4 will hold up to that for very long.


http://www.kalittacharters.com/

Contact me at tnjpriest@hotmail.com hope to here from you soon about the rear housing and axles.
5th (Jim)
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  #25  
Old 03-10-2003, 09:51 PM
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Default Re: Running fine

Quote:
Originally posted by johndarling
OK I fully convinced it's crap in the tank. As long as I keep it above 1/2 tank it runs good.

5th_Ave_Sleeper,

I live in Clarklake MI zip 49234. Just about 7 miles south of Jackson MI

John
Just a thought, back in my power boat racing days I had a triple engine tunnel hull that died during a race and after getting back to the dock it started and ran fine,but at WOT it would die. Turned out one of the foil sealers on a can of oil got into the gas tank and @ WOT it would stick to the pick-up tube. Those same type sealers are on gas treatments, have or do you use them
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  #26  
Old 03-12-2003, 07:41 AM
johndarling johndarling is offline
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Default Re: how bout thet rear housing?

Quote:
Originally posted by 5th_Ave_Sleeper
Johndarling,
Shoot man you arent to far from Willow run airport are you?
I work for Doug Kalitta at the jet charter service he owns.

5th,

No shit my father in law is a 747 capt for Kalitta air. Small World. I work down in Detroit so I drive buy Willow run almost every day.

John
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  #27  
Old 03-12-2003, 10:08 AM
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5th_Ave_Sleeper 5th_Ave_Sleeper is offline
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Too cool! yeah, small world eh?
I really like the idea of the fellow pages book. Lets get that rolling. Let me know if you need any help with that!
5th
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