QuestionQUESTION: I have a 1965 MGB roadster.
The car sat for 8 months while I was restoring the underside of the car. I took the surface down to bare metal. I remove the exhaust system, brake lines, fuel lines and the wiring harness from the engine bay down under the car to the trunk. I replaced the exhaust with Trophy exhaust header and exhaust system.
So 8 months later I go to start the car up. The engine cranks but does not fire.
I drain the fuel from the tank, replace the fuel filter between the tank and the fuel filter, replace the fuel pump and replace the spark plugs.
The car has a Pertronix ignitor, no points. I replaced that with a spare.
The car will start after about 15 trys and it will run roughly at 4k rpms and then stumple and die. Sometimes the fuel chambers are full and sometimes they aren’t. I’ve checked the needle valves each time to make sure the fuel is getting in the chambers. Sometime the fuel is there and sometimes the chambers are empty. I go to start the car again and I hear the fuel pump filling the carbs but the engine just spins over without a pop. Feels like no spark.
I’ve checked the voltage at the pump. It measures 11 volts. I have 10 volts at the coil. The ground checks out at the fuel pump and at the coil.
I’ve cleaned the inside of the rotor cap and all the contacts are clean. The plug wire connectors at each end have been cleaned and are shiny.
The fuses are new and the contacts are all clean.
The ground at the license plate if sound.
The fuel tank sender contacts are shiny and appear to work. Voltage there is 11 volts.
When the car runs it has a miss and runs rough. After about a couple of minutes the rpms drop and then increase and eventually the car stumbles and dies. Attempts to restart just have the engine spinning over with no pop.
Seems intermittent and I suspect the fuel tank may need to be cleaned out. But when the fuel chambers are full, the car should at least start if it were just fuel starvation. I think there is a ground issue somewhere or a bad distributor.
One other thing I noticed last time I did a dynamic timing last year. The timing mark bounced around quite a bit.
So I’m not sure where to attach this thing.
Options:
Clean out the fuel tank
Replace the distributor
I welcome any thoughts and I hope you can be of some help. This one has me stumped.
ANSWER: Hi Jeff. This sounds like a tricky one. My first reaction is that the car has sat for 8 months, so it could be stale fuel. Have you drained the tank and put in some FRESH fuel? Try this:
Take the lids off both float chambers, clean them with a piece of old rag, then half fill with FRESH fuel. Put the carbs back together and try to start the engine. If it fires and runs for a few seconds, then your problem is stale fuel.
Could be lack of spark. Hold one of the plug leads about 1mm above one of the cylinder head studs. (Beware of high voltage. Do not do this if you have a pacemaker). Get a friend to turn the engine over on the starter, while you look for a spark. If there is no spark, you have an ignition problem.
Next, remove the centre HT lead from the distributor cap, remove the distributor cap,and then hold the HT lead 1mm above the rotor arm. Turn the engine. There should be NO spark. If you CAN see a spark, then the rotor arm has failed and you need a new one.
I am concerned that the timing mark moves around. You did disconnect the vacuum pipe, didn't you? If the timing mark is not steady, the distributor could be shot. A Pertronix unit will not operate correctly in a worn-out distributor.
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QUESTION: I did drain the old fuel out and put in two gallons of 91 Octane.
The car will start eventually with this new fuel. Once started it only runs for a short period of time. The engine has a miss and runs roughly. If I run the rpms up to 4k and keep it there, the engine will begin to stall dropping the rpms down to like 2500 and then it will surge back up to 4k. Finally it sputters to a stop. The fuel chambers are empty.
If I try to restart, the fuel pump begins to click and the fuel is back up in the fuel chambers.
So the ignition does produce a spark. Question is what makes the car die and why is so difficult to start?
Is there an electrical problem that stops the fuel pump?
And why doesn't the car start when there is fuel in the chambers?
Could this be a bad wire somewhere in the loom that may have cracked when I removed it?
Any further suggestions?
J
AnswerHi Jeff. Stale fuel turns to varnish, so everything starts to gum up. Also, SU electric pumps do not like standing around unused. The die-surge-die symptoms are typical of when the carbs run out of fuel. On a 65 MGB the fuel pump is probably the older HP type with a built-in cylindrical filter. Undo the BIG nut and out it comes (along with some fuel). Make sure the pump has a good 12V supply and a good earth (ground) attached to the side. Also, give the points in the pump a clean. It should then burst into life, only stopping when the carbs are full. If it sounds slow and lazy, replace the pump.
