Won't start when hot

[94rangie]

'72 SIIA 88 with 2.25 gas engine. I drove it 130 miles today. When I got home I was backing it into the driveway, it stalled and wouldn't start. I'm pretty sure I stalled it. Since it was relatively warm today (65-70f), and I ran so long, the engine compartment was definitely heat soaked. This was also evident by the heat coming through the bulkhead. After about an hour it started right up and ran smoothly.

I had the same thing happen last year, but unfortunately not at the base of my driveway. I had previously replaced the plugs, wires, cap and rotor. This time I replace the coil, but had not run it hard and long in the heat until today.

I definitely have fuel and air, so I have to assume it is ingnition. What could be causing this? Points, condenser or timing? Could it be something with the carb? I have always noticed the Rover starts very easily when cold, even in the winter months, but on warm/hot days after being run it is takes longer to start. It is only after a long hot run that the Rover will fail to start.

Larry M.

[LaneRover]

Any chance of vapor lock?

[bmohan55]

I fought vapor lock for a month, I thought I was clogging fuel filters because as soon as I changed out a filter along side of the road...thus releasing the vapor lock..she started right up! I re-routed the fuel line, tiying it off on the oil fill neck and the heater control valve and it took care on the problem.

[Jeff Aronson]

The outside temperatures you indicated should not cause vapor lock on a Rover, but as Brent says, you might have experienced it. After 130 miles of driving, you'll feel the heat from the Rover drivetrain but again, your cooling system should be keeping the engine at a reasonable heat range.

So is the car running hot according to your fuel gauge? Is the radiator uniformly warm after shutting down the car? If you have a cold spot, then you have a circulation problem that's causing extra heat in the engine not reflected in the reading of your gauge.

Have you checked the plug gap and then timed the car? Advanced timing will give you more power but will also make the engine run hotter and then start harder once it is turned off.

Have you ever done a compression check on the engine? If you have low compression on one/two cylinders, you might not notice the slow drop off in power but it will afffect your starting when hot.

This is less likely but you don't say which carb you have, but you might be getting some metal expansion under heating which is opening up an air gap. That would make the car very hard to start. Are the carb base to manifold, and carb float cover both tight? Have you sprayed any WD40 around the carb when the car is idling, and if so, does the engine rev up slightlly. If so, you have an air leak there.

Good luck - it's probably not something serious.

Jeff

[StX_Rovers]

If you are running the 2-barrel Weber you could be having an issue with the fuel getting hot and pushing out of the vent causing a flooded condition. Does putting your foot on the floor, leaving it there and then hitting the starter until the car starts work? If so, you have a flooded condition.

Pierce manifolds sells a spacer that will help, if you have teh 2-barrel Weber. The spacer helps insulate the carb. We will be trying that on my wife's 88 which always started great cold, hard when hot. We have rebuilt the 2-barel Weber carb going down one size on all jets and up one size on the air correctors. We will see how it goes after we get the head back form the machine shop.

[adkrover]

Check the route your fuel line takes. It could be getting too hot in the line. Maybe a piece of sheet metal as a heat shield if you find a place where the line is subject to excess heat.

[94rangie]

Thanks for the ideas.

I have a weber. Sorry, don't know which kind off hand.

If I can see and smell fuel in the carb when I pump the accelerator, so I assume it is not vapor locked.

My next step is to install new points and condenser (been meaning to do it anyhow) and time the engine.

Holding the accelerator down and cranking forever does nothing but drain the battery.

No indication that the engine is running hot according to the gauge.

[Jeff Aronson]

Check your private messages.

If you can see only one throat, then you have the most common single barrel Weber. The weather and your sea level location really work against vapor lock as a likely problem.

Do look inside the fuel bowl of the carb by removing the top cover and peering inside. If you have a lot of junk in there. you will need to clean the carb. If you're holding the accelerator to the floor and cranking, but nothing's happening, then you're likely not flooded either.

If you have the combined oil pressure/water temperature gauge, then you have a fairly reliable unit. The electric ones can suffer from sending unit problems. The best test is to feel the entire height of the radioator after a run; there should be warmth throughout the unit.

A bad condenser will also allow a car to start easily but the car's running will degrade and eventually stop. So with new points, condensor - and I would advise a cap and rotor, too - you should be fine. Let us know how you make out .

Jeff

[bmohan55]

Actually a quick question to Jeff and some possible insight to the OP.

The PO of my truck had the fuel line sitting on top of the valve cover...I didn't know better and kept it that way. After getting the truck up to operating temp, if I would shut it down for 15 or so minutes and go to re-start it would start and drive for a short distance but die within a few miles. I assumed I was still pulling unseen crud thu the line so I'd replace the fuel filter and it she'd re-start and run fine. Finally I thought of vapor lock...I was burning the fuel in the carb and what was in the line past the valve cover and then stalling from fuel starvation. Opening up the line to replace the fuel filter released the lock. After I re-routed the lines around the engine my problems went away. Think my diagnosis is correct or serendipitous?

[scott]

i have the same issue. po had fuel line routed over the valve cover, hot = stop. i rerouted fuel line up on the bulkhead, still would shut down as if fuel starved when hot. so when i finally get the motor back in i plan on running the line low on the right side the up and over just behind the fan (i hear that that' the original route) and back to the weber 2brl. i hope this works as the electric fuel pump didn't. it's also been suggested to me to put in a return fuel line so excess fuel runs back to the tank to cool rather than building up pressure at the float valve.

[gudjeon]

Difficult hot starting was cured for me by this fuel filter and making a return from the small output line back into the tank. Hook in line near the carb and no other fancy fittings needed.

http://www.power-21.com/FramPower21i/Image.aspx?f=images/Fram/G3499_062408.jpg

[oldredbugeye]

hold it to the floor

when your vapor locked..you can hold the gas pedal to the floor..as long as your throttle linkage and springs are hooked up right..soon as you hear her fire..let of the gas and it will come out of it..i used to have this problem"vapor lock" when i had a rochester carb..but since going to a weber 1 barrel it has never happened again

Bill
Porter maine