I got my mostly stock 50 merc running a few weeks ago thanks to you guys here. I've put around 200 miles on it in that time. I'm noticing the longer I drive it and let it sit it doesn't want to restart. I've read a lot of threads and most say to add a phenolic plate. Since I have an electric fuel pump is this still relevant? When the motor is bone cold I have no issues at all starting it and it'll start the motor in less than 2 turns without touching the gas. So far it hasn't left me stranded but it's getting very close. I drove it for all around yesterday and shut it off 4x going into random stores, 20 minutes or so at a time and it was taking more and more cranking with each stop. The last time I stopped was roughly an hour being parked. By that time I had to crank it excessively between letting the starter and wires cool down. Then it lit off and was rough starting at first then all was good. At that point I took it home and parked it. Any good ideas?
After shutoff you’ll see a lot of Holley94’s and strombergs leaking. Most times it due to residual pressure between the pump and carb (after) it’s turned off. I have this (leak) issue on my stock distributor 94’s and stock pump on one vehicle. But my other vehicle with an electric pump and strombergs and electronic distributor , I don’t have this (leak) issue. The electronic distributor runs for two seconds after shutdown but the pump shuts down immediately. This relieves the pressure in the gas line. You may be flooding the carb??? Try shutting off your electric pump before turning off the ignition??
In case you're not familiar with driving carbureted vehicles, are you aware of how a "choke unloader" works? This is what comes into play when holding the throttle wide open when attempting to start a flooded engine. It assures that the choke valve is also held open to prevent additional flooding while cranking the engine. Check the specifications for your specific carb and look for an adjustment for the choke unloader. They don't tend to get out of adjustment but may have been assembled incorrectly during a previous carb rebuild.
A common problem with these. Also check your float level and be sure it's right. It's a percolation (boiling gas on shutoff) issue and I have lots of experience with this problem. Be sure any anti-percolation features in the carb are clean and open. Some use a little valve in the carb to handle this and others use an open to the atmosphere tube. I don't have much good to say on those "teapot" carbs. I have always hated them and used any excuse to not have to work on them. If your electric pump is the primary, only pump, try putting a switch on it so you can turn it off and let the car idle a while to use up some of the gas in the carb before you shut it off. When the gas boils it forces it up and out the main jets, flooding it badly. Also, if it has the stock exhaust system check to see if there is a heat riser valve in the system between the two cylinder banks. Make sure it is not stuck and the thermostatic spring is present and working. Better yet, take the thing off and cut the guts out of it or just throw it in the trash. High temperatures under the hood only make this problem worse, too.
Thanks guys! My electric fuel pump is my primary (only). Holding my foot to the floor doesn't seem to make a difference when this happens. There's no leaks on my carb, I just went through and rebuilt it, floats are set correctly. I'll be getting a kill switch for the fuel pump installed before I take it out next in hopes that takes care of the issue. I installed a check valve just after the fuel pump while I was troubleshooting getting it running initially. I may make a spacer plate for the carb too just to get it off the intake manifold to stop the spread of heat. It does have the stock exhaust with the cross over and butterfly valve on the passengers side, it's junk, I have it wedged in the open position currently. This winter I plan to put duals on it, wrap everything i can with header wrap and will eliminate the butterfly valve all together. Hopefully all of this takes care of it and I cam move onto the next improvement.
How is your fuel pump controlled now? Key on and it runs? You may have good luck with running a return line, use a chrysler fuel filter mounted under hood for the return line back to the tank. That will relieve pressure from fuel boiling in the line and give the cool fuel a place to go when you key up the pump before cranking.
I used to give the speech below on average more than 10 times daily for this issue. Now that it is in the troubleshooting section of my website, down to only 3~4 times daily. https://www.thecarburetorshop.com/Troubleshooting.htm#Hardstarthot It costs nothing to try it, and hundreds of customers have called back to affirm that it solved their starting issue. Jon
Yes, key on, pump on, key off the pump is off. I do have a regulator with one "in" and two "outs" maybe I could use the second plugged one as a return if need be. I'd rather not run a return line though. Carbking, I have tried this method during troubleshooting and it does work and is how I am able to get the car started. It has not left me stranded yet because of it, close but not quite. If I can stop the cause of fuel boiling from the get go I'd rather do that. I'll make a spacer for the carb and install a switch in the fuel pump.
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