FUEL SYSTEM GHOST " UPDATE "

[Steve P.]

The car is VegasMike's 68' Charger. The problem is keeping fuel pressure and volume in the bowls. This car has been rebuilt from the ground up. New everything from the fuel tank to the carb. Including all.

Here's the scenario. Going back a few months now, it was running a Holley pump. Then another. Then another. Start the car cold and read 7.5 lbs fuel pressure. As the engine warms up the pressure drops off. By the time it gets down to 1 LB. the pump is hotter than hell and has had it.

Before you ask, NO there is no return line on this car.. Yes there was a regulator and he changed the gauge 2Xs. Also can see loss of fuel in sight glasses.

Next:: Was going to a Carter Street Pump. After many checks and much though, we cam to the conclusion that it had to be a heat problem coming from the headers and mufflers being too close to the pump. Or the pump being too high. Or a combination of the two. Or God knows what else??
                                                                            SAME RESULTS

Next:: to make sure we had no restrictions, Mike filled a fresh gas can and set it far away from the car. Ran fuel hose plenty far away from the car so that in NO WAY could you blame anything on heat anymore and still got the SAME DAMN RESULTS.

Start it cold,7.5 psi. fuel pressure and the bowls stay right up there.
About 5 minutes go by, the temp is up to 180* and the pressure is down to 3 psi.
By 7 minutes it's at 190*, 1psi fuel and the bowls are just about out..
This is sitting in his driveway, idling at 850 - 900 rpm. the cars tank or a gas can. Multiple new electric fuel pumps and now a brand new, just installed Carter Street Pump and the weather is only about 70* out there right now.... (((((AND THE HOOD IS UP)))))!!!! It has a wood spacer between the carb and manifold. the bowls get warm but not anywhere near hot. fuel delivery is cool.

Any ideas??

I may have left some things out but don't leave any questions out.. I have to have missed something.. I don't care if you think I forgot to open   the sneezer valve behind the spare tire grease fitting!! ASK AWAY!!!!

[Runner]

is the street pump an electric of a mechanical?,  where is the pump mounted and how is it wired?.  im sure you guys know electric pumps like to push the fuel not suck it.   

      if the street pump is mechanical have you tried pulling the regulator out of the system?., the street pump shouldnt need it.

   if the pump is electric, have you tried to just let it pump with the engine off and see what happens?.

     

[Steve P.]

The Carter Street pump is mechanical and he took the regulator out of the system. Also has a brand new MP push rod.

[Runner]

wow this is interesting.   it might be interesting to use an electric fuel pump out of a can with a well insulated hose straight to the carb and see what happens.   it sure sounds like a vapor lock issue.

[Steve P.]

That's what we have been thinking all along. ((( BUT ))) Vapor lock doesn't eat new pumps and normally is not an issue sitting in the driveway idling in 70* weather with a gas can as a fuel source!!!


Many things may come into play here and we don't care what it takes to fix it. Just that the son of a bitch is driveable.......... 

Tomorrow, (Christmas day), Mike is going to set the gas can up with some fuel hose and an electric fuel pump. Go right over the top of the damn fender to the Friggin BG carb and see what happens.

If it takes a hood scoop and a ten inch thick phenolic spacer, so be it!! If that fixes the problem, it will be...

[Runner]

any chance there is a restriction in the line from the pump to the carb?.     im almost a little embarrased (ok im alot embarrassed) to tell this story but here goes.  i kept having tranny problems, at first i thought it was a warn out tranny so i rebiult the tranny .  it was my first rebiuld and worked great for a couple monthes, then it would loose 3rd gear and the band would burn up. id take it apart and check everything and reassemble with a new band.  after about the 3rd shot i decided to blow through the braided tranny lines i made.  come to find out i had scooped a big chunk of the rubber hose up into the end when i assembled it basically plugging it.. on the 4th shot i did the hole tranny again, all new lines and a new cooler, problem solved.
   
       hmmm a 10 inch phonolic spacer sticking through the hood may be a real trend setter!

    is he planing to get it to the track anytime soon?.   im really curious to know how it runs.
                               

     

[Steve P.]

All lines have been checked and changed just to be doubly sure. The motor runs like a raped ape up until it runs out of fuel!! Firefighter posted the dyno results on this motor a short while ago. He specked the cam for this motor after a different fiasco.

Fuel injection is sounding very good right now.. I know it sounds stupid, but this is killing me LONG DISTANCE!!!

[firefighter3931]

Hi Steve, been thinking about this since i got your PM. It sure sounds like there's some type of restriction on the inlet side. I'm going to assume Mike blew the lines out with compressed air. Have the lines been checked for kinks and sharp bends ? How about the sock in the tank...is it possible that it's clogged ?

Here's something else to consider : How much rubber line is between the tank and hard line ? What type of hose is Mike using there ? What i'm thinking is that the rubber hose is collapsing and creating a restriction which is causing the reduced fuel pressure as the engine runs for extended periods after startup. This would account for the overheated and burnt electric pumps.

Initially on fireup the carb bowls will be full but as the fuel is being used up and the pump is sucking it is slowly collapsing the hose. Have Mike take a peek at the rubber line between the tank and hardline for a few minutes after startup to see if there's any sign of collapsing. The fact that the fuel pressure is dropping the longer the engine runs is what i'm basing this theory on...hopefully i'm right. A chunk of braided hose will fix the problem, assuming that my theory is correct.

Ron

[Steve P.]

Sorry Ron, I should have mentioned it earlier. The car was put back together with all new everything. Tank, sender, lines and in between is braided hose. All of it checked and rechecked and then replaced at my request just to humor me..   The trial today was with brand new rubber fuel hose wide open in a fuel can placed off to the side of the car away from the cars heat.. Same same...   


This is killing me!!

[firefighter3931]

Sorry Ron, I should have mentioned it earlier. The car was put back together with all new everything. Tank, sender, lines and in between is braided hose. All of it checked and rechecked and then replaced at my request just to humor me..     The trial today was with brand new rubber fuel hose wide open in a fuel can placed off to the side of the car away from the cars heat.. Same same...     


This is killing me!!

There's got to be some type of restriction on the fuel sending unit then. The sock is plugged or something is in the line.

Ron

[Steve P.]

Today Mike put a fuel hose from the pump to a fuel can 90 DEG. from the front of the car and ran the car from cold until it did the same routine all over again.. So that takes the tank, sender, fuel lines, exhaust out of play...  

HOW EVER,,,,,,   answer me this :::::   On a Carter Mech. pump at idle, needle and seat shut or open, cold motor or hot, shouldn't the fuel pressure still be maintained @ 6-6.5 psi ? Regardless of a return line??

[Steve P.]

It has got to be vapor lock..........................   I just don't know why!! It's done this shit when it's been down right cold out!!!!!

Can vapor lock destroy MANY electric fuel pumps?? Good Holley's??   That has got to be it!!

[Runner]

steve, my mechanical carter strip pump at idle puts out well over 11 psi with the regulator cranked wide open.  i reg it down to 7 psi. the strip pump is rated at 8.5 psi..so its putting out a fair bit more than what its advertised at. so id think the street pump should be about 6.5 psi at idle.     how about a fuel filter (ya ya i know youve either already thought of it and checked it but i had to ask.

     your brothers engine is simular to mine, right down to the bump stick, thats why im interested in what it run at the track... and i like to here results

[Steve P.]

Yup, it's a STREET pump and it will put out 7.5 dead cold with NO filter in line...

No track time on the car yet. Still working the bugs out of it.. Between the amount of hours he puts in on his job and the lack of competence around Vegas he is ready to kill someone.. On top of that he starts work about the time the sun makes it's appearance and gets home right about the time the moon does... 

I'm thinking it's time to try some clothes pins.....

[Chryco Psycho]

either a plugged fiter on the pick up tube or a pin hole in the pick up tube starving the pum & overheating it

[Steve P.]

No,, Mike has eliminated the cars fuel system all the way up to the mechanical fuel pump by using a gas can and new fuel hose set away from the car. Right now there is NO fuel filter in line at all.. Just a clean gas can with fresh 92 octane, fuel hose leading to the Carter street mechanical pump and new fuel hose to the 3/8ths duel feed w/gage to the 750 Mighty Demon.


I have been beating my head against the wall on this.. The only thing I can come up with is Vapor lock.   I would not have any trouble believing this except for the fact that this has happened on this car when it was damn cold there also... Vapor lock is not normally an issue when it is cold.. And coming from the North I can tell you that I personally never experienced it or heard of anyone having that problem when it was cold....   Then again, maybe being at 2300 feet above sea level has something to do with it!!    Any rocket scientists here??

[Runner]

how is the hose from the pump to the carb routed?.   i did stay at a holiday in last night!

[Steve P.]

Hahaha..... I was going to pull a Geico (GOOD NEWS), JOKE, but you know!!

The routing USE to be from the regulator on the inner fender, behind the alt, to the fuel feeder. Now with the Carter mechanical it is routed up behind the alt close to the factory setting and to the duel feeder..

Today he is going to change it all around. The fuel line will be run as far away from any source of heat as possible and also he is going to try running another electric pump from the gas can and way away from EVERYTHING.....

If this doesn't do it I am flying out there and loading the shot gun myself!!!

[Steve P.]

Well, change in test.. X-mas day was a bust as far as testing. The only test was a gas can, mechanical pump and using plenty of hose to stay away from heat sources. The duel feed fuel rail still is in the front feed position and it is still shitting the bed after it warms up... 


This is a nightmare... 

[beenaround]

steve is it possible the fuel pump push rod has worn the lobe off the cam???as for the electric pumps,is the wiring of a large enough gauge to carry the amps and volts needed??you may want to tie an amp gauge in line and see if the amps go up as the motor heats up.this would mean that the pump is working harder.also did you try to use the pumps on another car???

[Steve P.]

Good thoughts, but yes we have been there too... Plenty of power to the pumps. and the New mechanical cam is being pushed by a new MP rod and a NEW Comp Cam.. The chances of this being anything other than vapor lock are very slim at this point... 

Mike was going to do more testing today, but Vegas has very high winds and it's not a good idea to have the carb opened up in that sand pit..

[firefighter3931]

Keep us updated Steve. Just wondering if the demon has filters on the bowls where the lines thread in...like the holley carbs do ? I've seen those clog up and cause problems....i allways remove them, fwiw.

Ron

[Steve P.]

Good question Ron, but I can't imagine if it has them they could be clogged up already. It hasNOT been through a tank of gas yet!!

Will definitely keep you infomed.. With a little help from the weather man tomorrow......

[Ghoste]

Have you tried a different carb yet? 

[Steve P.]

3 carbs in all. Same same....  Today he changed the routing to the back of the bay.. It took longer for the problem to show it's ugly head, but it showed...  He turned up the pressure at the regulator and she kept up then.. It's fot sure vapor lock.. He's got to put a thicker spacer between the carb and manifold.. The one in there now is a 1/2" wood.. I'm trying to talk him into a 1" phenolic.

The only thing I don't get about the phenolic is that the hole diametor is rather small.. 1.4?? X 4.. The plastic is 1.750 X 4.. Why such a difference?? I have been trying to get in touch with the makers of them, but it's the hollidays ya know!!