Need help trouble shooting fuel issue....

[Xavier]

Here it goes....I have had this problem since I built the car, it usually is quickly remedied, and was going to put off the repair until winter, but I can solve it this time...

After a couple of weeks of having my car down and out to replace the exhaust manifold gaskets and to eliminate some annoying back-firing, I once again, am having problems getting fuel to my engine. Its importnat to note that prior to this downtime, the car was running very well. No issues at all - other than the annoying backfiring which for a fact was due to a blown exhaust manifold gasket, I replaced both gaskets as normal, torqued down etc. Since th cork valve cover gaskets were leaking in the process, so I took care of this too. I also replaced the carb manifold gasket at this time with a new one. Pulled off the carb and replaced the gasket. I really did not need to do this, but when I put the new carb on I used the old gasket, it did not look so hot, so when I got a new one I vowed to replace it, so I did.

I go to start the car, and what has happend before after having the car down for a couple of weeks is the fuel pump gets no fuel to the engine without a huge process of different unorthadox techniques. It has done this many times, and to get it up and going this is what I have had to do.
I turn on the fuel pump, I know there is no fuel to the engine becuase my PSI gauge at the carb is at zero, and I am just used to this...I loosen one of my -AN fittings until the fuel bleeds out near the carb, catching any fuel with a rag and having a wrench ready to tighten the fitting. This may take a few minutes...the longer the car has been down, the longer it takes. Fuel starts flying out, I tighten the fitting, go start the engine, and I am good to go...its annoying as hell, and I vowed to fix it, I just did not want to do it now.

My fuel configuration is as follows;
3/8" fuel line / -6 fittings
regulator / no return line
Holley Black fuel pump mounted behind driver side rear tire
course filter before pump, fine high capacity canister filter after - both clean
The pump is higher than the lowest part of the fuel tank by about 6"

So I go through the process I have done previsouly, except this time - the gauge stays at zero - very little fuel if any is coming out. I take apart my fuel pump and it looks totally burned up - black. Smelled bad. I replace it whith a new one this evening. I bolt it back up and go through the same "bleeding process" as before. The noise or pitch of the fuel pump changes when it is under load, so by listening, I can tell when the fuel is getting to the pump. This time, the fuel is in higher pressure, pissing everywhere. PSI is at an unstable 5 to 7PSI (I have the regulator set at 7 just to get this thing going temporarily). Still, the carb is leaning out - acts like there is no fuel - although there is. Fuel sites in the carb show 50 to 60%, as usual. When starting the engine, if I keep pumping the pedal, the engine will run, but quickly dies when off. I don't want to cause any engine damage, so I kill it. Way lean.

Carb is a Summit Racing 600cfm carb (4010 clone) - again this carb has worked perfectly up to this point. No issues. No performance problems at all.

So, whats the issue?

- Did fixing the exhaust headers, valve covers, carb gasket cause another issue and changed the performance of something else that drastic so the carb is now out of whack? Hard for me to imagine it when from perfect to no gas.
- Did I screw up something when changing the manifold gasket on the carb? Something get into the carb?
- I know something is screwed up with the fuel process, that's a given - but again, it worked before - why not now? Warmer temperature causing vapor lock? Its not that warm...

I have my old Edlebrock street carb that I can switch out, I plan on doing it just to see what happens becuase I am running out of ideas.

What do you do when your car gets gas, but it acts like it has none?

I am out of money, out fo ideas and out of time before the weekend. Anyone have any suggestions, please?

[Rick Parker]

It sounds like the pump is losing its prime when it sits. By design Rotary Electric pumps push fuel better than pull it. Are you pulling fuel from the top of the tank or the bottom If you can, mount the pump so the inlet is even with the bottom of the tank. I think electric pumps do not have enough benefits to outweigh the negatives. Check the pressure you are running, be sure the carb is capable by design of accepting what you are asking it to.

[Xavier]

The pump is in fact higher than the outlet that is at the bottom of the tank. I am trying to pull from the bottom, but it is impossible to mount it as low as the bottom of the tank. Its just not going to happen....you are right about everything you say, its a mod I am going to have to do - but mind you - its been running this way. I am thinking of having a tank made so that the pump can be mounted at the lowest point...but for now, this is what I have and it has been running...

The pressure for the carb is normally set to 5.5, I am just playing with the regulator to get something out of it - and even if it can't handle it - why would it act as if it has no fuel at all? Why would it die as soon as I lay my foot of the throttle?

[CHANMADD]

I would agree that the pump needs to be at least level with the bottom of the tank. Also...why not go to a mechanical and solve your problems for good and at a lot less money??
John

[RICK LAKE]

Xavier A one way check valve would help keep the drain back problem from happening. Couple other ideas. you have P-mail Rick L.

[Clois Harlan]

Xavier,

Go to Lowes or Home Depot and get a piece of 14 gauge steel plate 6" x 6" and make a bracket to mount your fuel pump. Use some self threading screws if you can't weld it to the rear frame. Mount your bracket and pump behind your pumpkin level with or lower than your fuel cell. I went and checked a friend of mines Lonestar and this is easily done. I think what others have said is that your fuel pump is loosing it's prime. I would also check all joints where your fuel line is joined with a union or hose clamp to make sure everything is tight and not allowing air or a minor leak.
Good luck and let us know what you figure out.

Clois Harlan

[Xavier]

Its seems for now - something quick that I may just stick with - if just getting a mechanical fuel pump and be done with this. Easiest, cheapest route. I could try to mount the elctrical pump correctly, but at this point, it going to be a ***** to do and the outlet on the supplied tank is in an "extremely fragile" state due to design. I am afraid to even look at the damn thing. I am going to save up for the stainless one, but thats another subject.

For sure - I have absoluley no leaks.

Easiest, cheapest thing to do, to enjoy driving the car - all the time - is just put in a mechanical fuel pump.

But I am still puzzled - why its spitting fuel now, its under real pressure - but the car still acts like there is no fuel. Air? I don't get it. How can there be fuel spraying like a garden hose and still the engine acts like their is no gas?

I will get the mechnical now, but although we addressed the long term pump problem, I still don't get why it won't start today.

[DAVID GAGNARD]

Having the pump higher than the tank is causing it to drian back into the tank when you let it sit for a while and when you turn on the pump, it runs "dry" till it picks up the prime, that's what caused the pump to burn up. It's also harder on the pump having to "suck up" the fuel,then pump it to the carb. Having the pump lower or at least even with the tank will let fuel somewhat "siphon" into the pump, a lot easier on the pump.....

Personally,I don't care for electric pumps, since the mechanical ones last for years and thousands of miles trouble free.......

David

[vettestr]

A bell went off when you said "(the outlet on the supplied tank is in an "extremely fragile" state due to design. I am afraid to even look at the damn thing.)" What if the connection was allowing air to be pulled into your fuel system on the suction side of the pump?

A couple of thoughts here..... As you know electric pumps do not pull well as they are designed to push. Make sure fittings are sound so air can not be pulled into system. Install a P-Trap in the hose between tank to pump by making hose a little longer and allowing center section to sag. Sorry for description here but I am trying to make a low spot in hose for fuel to stay in so it picks up a prime quicker. Get rid of the filter between tank and pump as this is a huge restriction on a set up with problems already. I think the filter is hurting the prime big time. Regulators do not like air and gas so fixing inlet may resolve that problem. good luck jeff c

[Xavier]

That filter between the tank and the pump is very coarse, just a metal filter to prevent large contamination from entering the pump - not a fine filter. Trust me, it won't restrict it.

Thanks for the advice; my experience with gas leaks is this (if I am wrong correct me). It is extremely apparent if you have a leak - your entire garage (regrdless of the qty of gas) smells like gas - really - really bad. I have had a small, small trickle before - and you KNEW you had a leak. Hard to see, easy to smell.

Since gas is extremely thin, and kind of spreads out (unlike water) gas seems to be able to seep into plastic and the SS hoses without being entirely visible and without dripping. But the smell is the dead give away...

Assuming all of the hoses are tight, the ends are tight, etc. How important is it for the top of the tank (where the sender is) to be sealed perfectly? I would assume an air link there is irrelevant becuase nothing is trapped in the fuel line process to the pump - correct?

[Tommy]

Regarding the poor running engine - If you are certain there is ample gas at the right pressure reaching the carburetor, and you are certain the engine is running lean, then something must be wrong in the carb. Perhaps when the old pump failed or when you removed the carb something disturbed the floats or clogged up the jets. Check them.

Regarding the fuel pump losing its prime - You said the pump is about 6" above the bottom of the fuel tank. Until you can do a permanent fix, try topping off the fuel tank with gas whenever you will be leaving it for a while. Maybe you can keep the level of gas in the tank higher than your fuel pump.

[RedBarchetta]

If you do go to a mechanical pump, make sure your engine has the pump eccentric already mounted to the front of the camshaft. Some builders that know if the buyer is going to go electric will leave it off entirely. Mine came loose once (the dowel pin used was 1/8" too short when installed) and it was quite a bit of surgery to just fix it (pan off, balancer off, water pump off, front timing cover off, etc.). Major PITA for a $2 steel dowel pin! @#$&% RDI. But it's now rock solid and you know it's reliable when done right. Good luck either way you go!

-Dean

P.S. You can use a mirror or bore scope and see the eccentric quite clearly through the fuel pump mounting hole.

[Xavier]

Thanks Dean,

It came with one and I took it off, so it should be there. Ironically, to fix it, I have to go back to what I had. Had to do some shopping this morning at the local speed shop....

[bakbutler]

Xavier
As vettster suggested check fuel lines on the "draw" side of the fuel pump. If you have a "pin hole" leak the pump will suck air which would account for your erratic pressure. You may not have a fuel leak at this point because there is no pressure on the line.
Leo

[RallySnake]

Xavier,

I have driven my Arntz Cobra for 20 years now. I have driven across the country and on many long distance rallies. I have used about 6 or 7 fuel pumps (I've lost count). I would never drive the car anywhere with just one electric pump. I have been stranded three times and sworn that it will not happen again.

There is no room next to my engine for a mechanical pump, the headers are in the way. I run a Carter high performance pump and a cheap stock type pump both mounted to the frame behind the passenger side rear wheel. I have an Oberg course filter for the fuel to go through before the pumps and a big metal can stock filter after the pumps. The pumps are plumbed together with a 3/8" Y connection before and after.

Electric pumps are fragile hard working components and are not to be trusted. I put a push button switch next to the key switch in my console for the second pump. For 20 years that has worked fine. I highly suggest that you do the same. It really helps when you're in the middle of west Texas (nowhere) and the primary cuts out.

I push the button when the primary pump fails and the secondary pumps turns on also. However, that bit me big time in a rally a few weeks ago. The primary Carter pump has an internal regulator that failed putting high pressure to the Holley carb. It flooded and killed the engine. I had to crawl under the car and pull a wire off the Carter so that the stock pump could supply fuel at the right pressure. We missed two checkpoints and lost the rally.

I have installed a simple relay that now switches from one pump to the other.
From the description of your problem, I believe that the problem is the pump itself. I don't care if it's brand new. My first Carter was a month old when the vane rotor started slipping on the motor shaft. Another time, the screen inside just got full of crud. You need to take the pump apart and find out where the problem is. And....buy another one!

You did not mention the level of fuel in the carburetor. Does it have sight glasses in the tanks or a screw cap to check the level? It is really important to know that the fuel is at the proper level. Two other things to check. Sometimes, when you turn a carb upside down, the float can get stuck. Sometimes, a little dirt can stick in the needle and seat open and cause flooding.

[Xavier]

Well, thanks for all the replies - Thanks Rally Snake - those are all good things to consider, espescially coming from a proven driver by the way (how many miles do you have on your Antz?). I have in fact took the pump apart and it is working properly. I can compare it to other measurments I have taken on fuel pumps that have worked with a fuel vacuum gauge, I also dismantled it. It is at 100%. I too know how the term "brand new" does not mean anything...all too often.

Yesterday, I took everyone's advice and purchased a 110gph mechnical pump with -6 lines and -AN fittings. All in all, it came to about $239, which I could have gotten off the internet cheaper, but really needed it for last night.

Although the larger volume mechnical pump is very large - scary large (is it going to clear?) it did. I stayed up until 3am lat night putting it on checking it out and not being able to start it until this morning.

It fired up perfectly. I dialed in the regulator pressure at 5.5psi as previous with no issues. Very clean and easy. Ran great. Started easily...wow, what a headache.

Now since I have the electrical pump, the fittings and everything in-line (I know its in the wrong location, or at least the wrong height) - should I rip it off (can't return it) or at another date plump it correctly? I guess what I am asking is - is there an advantage of using both in-line for some reason - or to plumb it correctly in the future as a back-up to the mechanical pump...

What would you do with the electrical pump? I just don't want to dump it.

[PANAVIA]

Caustic, -- reducing the complexity of the fuel system , removing the electrical pump and having nice clean lines may be a long term reliability proponent.

the fuel starvation issue for some reason sounds like vapor lock or bad angle causing air to leach back into the system. --

the other point I would make is that fuel line should be a cool as possible, using good quality insulation where possible and locating the fuel line as far away from moving/ hot components. (normal no biggie stuff)

--Steve