starting problems

[Ratbird]

Actually, it's a "restarting" problem. This could be a dumb question as I'm a rookie and this is my first motor.
I have a 390 with a 428 crank, Edel RPM-performer intake and 750 carb, C4ae heads with CJ428 size intake valves, headers, and Lunati's version of the 428 cam - see the specs here for the cam - http://www.lunatipower.com/Product.aspx?id=2269  and a Pertonix ignition instead of points.

So what happens is that if I drive it for more than 20 minutes, then park it for approximately 20 - 60 minutes it's real tough to restart. If I drive it for 20 minutes and shut it off to get gas, or something that only takes a few minutes, it'll start right back up no problem. It usually eventually starts with a lot of cranking and flooring it like it's flooded. I've tried starting without any pedal, with a single pump, or 2 or 3, etc. Oh, and once it does start it will stall if I don't keep it revving for the first 5 minutes. It's a 4 speed and it has a manual choke.

Any ideas, or experience that you have would be greatly appreciated.

thx, Dave J     

[machoneman]

It's a common issue with older, carb equipped cars. Anything one can do to eliminate heat around the carb, lines, fuel pump will help. Also, if your engine has one of the OEM Ford heated carb spacer (routes one of the heater hoses through the hollowed-out spacer for better fuel atomization) under the carb, dump it and use a solid wood/plastic/phenolic spacer instead . 

http://www.edelblog.com/tech-tips/resolving-heat-soak/

http://www.fordification.com/forum/viewtopic.php?f=3&t=58537&start=0&st=0&sk=t&sd=a

[Lenz]

What comes to mind for me was discussed a while back in this forum, vapor lock.  There are other things that can cause your problem, but the time factor is what interests me.  A couple of minutes and no problem, longer and a battle.  My initial guess is that fuel sitting in your supply line (or carb? )while not running is getting cooked somewhere along the way.

I'd look over your fuel supply line from the tank forward to see if you are too close to any high heat sources, especially right above.  Since the car does not stall out  while driving it may not be obvious, but it's worth a check IMO. 

[cjshaker]

Yep, like Bob said, it's probably percolating gas out the carb into the intake. What he said is good advice, and I would add check your float levels as well, maybe even drop them a bit and see if that helps. But keeping heat away from the carb will likely help or cure the problem. Do you have an actual temp reading guage to see where your engine is running? Also, if your exhaust crossover in the intake isn't blocked it can add to the problem, but I can't remember if the RPM has that or not.

[drdano]

One test I would try is locate a gas station that has no ethanol in their fuel and put a tank full in and see if it makes any difference.  That would raise the boiling point of the fuel a bit and it would be interesting to see if it changes the behavior.  If so, you would know at least a contributor to the problems.

BTW, I'm in the same boat with my wagon.  On a hot day when I park it in the garage after a run around, I can hear the float and needle "jiggling the handle" from the heat and modern gas. 

[machoneman]

Have the same issue in my '70 Mach 1. I'm careful on a hot day to either a.) shut it off for only a short time or b.) once off, make sure I don't need to re-start it for at least 1 hour, or more.

One more experiment. Shut it off on that hot day and remove the air cleaner. Note at say 10 minute intervals any hazy, visible sheen or heavy gas smell over the carb. That's gas evaporating from the fuel bowls as engine heat starts to cook-off the gas in the bowls. 

As mentioned too, today's 10% ethanol laden gas also is a contributor too as it more easily boils off than straight gasoline.

Note too a older, weak fuel pump can contribute. The rubber diaphragm inside the pump can weaken with age, allowing fuel on shut off to drain down away from the carb's fuel line. An electric fuel pump may be a cure as once the key is switched on, for say a few seconds before actual engine start-up,  the pump refills those empty lines all the way up to the needle/seat in the carb's fuel bowls.  This works for many to eliminate the hard start issue. 

[Ratbird]

Awesome gents, thanks!

It just so happens that I have a Jegs 1/2 inch phenolic carb spacer I was going to install. That should help cool the carb some. I'm currently using a generic inline metal fuel filter. It isn't touching anything, but I'll look for a plastic one at Autozone. The metal line from the new (stock) mechanical fuel pump doesn't touch anything either, but the rubber fuel hose from that touches the top of the intake. I'll route that to not touch anything. This all makes sense being that the aluminum intake does get pretty hot after shutting it down. BTW, the RPM Performer intake does not have the crossover like the original did.

I'll install the spacer and route the fuel lines this weekend and report back.

really appreciate the help!     

[bn69stang]

Insulate your fuel line from pump to carb as well , summit has some different wraps or you could try running aluminum 3/8 fuel line from pump to carb , the phenolic spacer will help i use there 1/2 spacer .. the gas these days is a pain . I even think Jay mentioned running an electric pump with a return line .. Bud

[Ratbird]

I have a metal line from the pump, that goes to a rubber line and the metal fuel filter, then rubber to the carb. Here's a picture. I have re-routed it so the filter isn't resting on the valve cover. I'll try the spacer this weekend, I'll also see if I can source a plastic fuel filter. If that doesn't help I'll have to consider the electrical pump. What's a return line used for?
 

[machoneman]

FYI, the return line is generally used with modern EFI engines (running say 30-45 lbs. of high pressure to the injectors) as most do bleed off excess pressure and fuel back to the gas tank. On older carb'ed vehicles, by using relatively low pressure electric fuel pumps with a regulator that doesn't allow more than the nominal 5-7 psi Holleys (and most carbs) run at, one can usually skip the return line. Many do though intentionally run higher pressure pumps and therefore must bleed off the excess through a return line.

There are more pros and cons to either way and the rationale behind the choices but I'll let others chime in. 

[Heo]

And the fuelpump pumps cold fuel from the tank whole the time
so the fuel cirkulate and dont have the time to heat up in the
fuel line

[Lenz]

From the photo you posted I'd really be wary of that line between the pump and carb. 

Looks like it could be in contact with the radiator "catch basin" (as I like to call it too.  Definitely want to get the hose and filter moved, they'll act like heat sinks when you shut the thing down.  In the past I've bought the hard line you can get at any auto parts store that you are able to bend easily enough without any tools.  Form it up so that it's a couple of inches away from anything hot. 

I've also stuck my filter between the pump and incoming fuel supply line where you currently have a length of hose leading to the hard line on the frame.  If your setup has the room you can do that too.

I realize these are el-cheapo type fixes , but if they help you identify and fix the problem you can upgrade accordingly.

[Drew Pojedinec]

If all the heat isolation and whatnot is done, I continued having this same problem.
In my case I ended up figuring it out, it was a weak coil that was mounted on top of the intake....
It was fine when cold or when running, but would get weak when it got hot, especially after shutdown.

I replaced the coil with a new one and mounted it to the front of the head. 

Just another thought

[Barry_R]

Really good to hear a follow-up once a problem is solved.  Helps everyone.  I have had an occasional coil problem, and they can be real "beggars" to diagnose.  To the point that - if I get stumped by an engine that does not run how it should - I'll swap out coils pretty quickly just to find out.

[Drew Pojedinec]

yeah, I learned that lesson Barry, I chased my tail for a long time, was especially hard as my experience was with a worn out 302 that I got with no history....  I'd like to hear what the Original Poster's issue ends up being also.