Bad Gas?

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72dustyer

72dustyer

All go, no show
Joined
May 29, 2005
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Location
Douglassville,S-East PA
I filled up with some of the $3.25 a gal stuff and now the car won't run right. This is only the second tankful I ran thru it since rebuild. It'll idle OK, but after a once around the block it stumbles and dies. I checked fuel pressure and it's OK @ 7.5 psi, which is what my 750 dbl pumper wants. I also emptied the fuel filter with no signs of contamination. Could it be bad gas? or is it something else like the wrong size powervalve. Bad gas wouldn't let me idle at all correct?
 
i would pull the plugs and take a look at them , to rich could mean a power valve failure, any backfire through the carb can ruin a power valve , it only takes once, unless you have a newer holley with the power valve protection . is it possible that you got some of that 10 per cent ethanol gas that they have here in the NE ? if so it may be to lean..my cars all hate that fuel..... even the 1500 ram hemi, that is suppose to run on that stuff..
 
I pulled the carb and found a peice of the thread caght up in the powervalve. I guess it got wedged in there when they put it in. Also put a vacuum gage on it and foun 6" of Hg at idle. I am guessing that I need a 4.5 powervalve to work correctly? It still stumbles when you touch the throttle and runs out after romping on it. Did I mention that I don't like setting up carbs?
 
see if your idle mix screws are set right. adjust to highest vacuum, then 1/4 turn in. check initial timing, find max vacuum, then back down about 2 hg. but then also check it at 2000-2500 rpm with vacuum advance disconnected if you are using it.
 
It's a 525\250 duration cam which I wouldn't say is monster. I just got back from the shore so I'll check and adjust the idle vac. I replaced the powervalve with a 3.5" so I'm hoping that helps and it does: I also got a liquis pressure gague and I show 6lbs of fuel but after I get her warmed up it drops to 3lbs. I'm wondering if my regulator has some debris in it or is just another little thing to make it not run right. I know it's fuel delivery and it's real close! :cwm10:
 
yep I think the regulator is bad. When hot I set ti to 6lbs, now it's cool and I checked it and its up around 9lbs. It's an aeromotive setup. I think I'm gonna go to the speed shop tomorrow and see what the dilly is. did I mention feul delivey is a PITA?
 
72dustyer said:
yep I think the regulator is bad. When hot I set ti to 6lbs, now it's cool and I checked it and its up around 9lbs. It's an aeromotive setup. I think I'm gonna go to the speed shop tomorrow and see what the dilly is. did I mention feul delivey is a PITA?
Click to expand...

Hot or cold, the fuel pressure downstream of a properly functioning regulator should not change. Here's my setup with filter, regulator and pressure guage.

P6110001.JPG
 
well, I checked again today no debris in the line, took the regulator apart nothing in there. I have my setup filter, pump, regultator, carb. It's getting frustrating because sometimes it runs fine then it lets me down. I'm thinkink of canning the electric fuel pump and going back to a stock setup. I even thought the gague was bad so I borrowed another from the speedshop and got duplicate redings. He did say that a liquidfilled gague will give a distorted reading underhood. Iguess i'll take the carb aprt again and see what I can find in there although I'm leaning towards defective regulator or pump.
 
why take the carb apart? is your electrical system running properly? check the voltage and see if a) the voltage regulator is keeping it under 14.5 volts and b) that the pump has a good ground. i would change the regulator first, it may have a bad diaphragm.
 
It's the regulator definately, I took it apart all the way and the ball check spring is twisted around itself like a slinky. I tried to pick it apart with a pin but no luck. So I went down(again) to my local speed shop to see if he got the new regulator in that we talked about swapping out the day before, and the effin d-hole didn't order it yet.
So I'm thinking of getting a $25 Holley one from the local parts store to see if it's the culprit.
 
allright last post on this thread... all weekend trcing fuel gremlins. Hardhead (me) had to have another fuel regulator for the weekend. blew out all the lines hooked up the temp regulator and still had the same prob. noticed oil around the distributor and yep it was loose it checked out @ 20" total so move it to 36"total and runs like a champ. Whooda thunk to check the easy stuff first? :silent: BTW I did miss the carshow in Pottstown too.
 
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