Mechanical fuel pump starting
baronbors said:
The old mechanical pump was getting weaker and weaker and getting harder and harder to start-
had to pump about 15- 20 times to get it started in the morning. Electric fuel pump- one pump and starts right up everytime.
Did you mean "pump" the accelerator pedal or turn the engine over "15-20 times"? Unless it's leaking gas, don't think "weak" pump has much to do with your "hard starting". Other than leaks, mechanical pump is pretty much "GO/NO-GO" . . . works or doesn't.
Assuming mechanical pump, let's briefly review generally accepted "carb engine/mechanical fuel pump" starting method. You pump the accelerator pedal twice to "SET" (engage) the choke and "prime" the intake plenum, then start engine. If still using stock joined manifolds and, especially if not using a phenolic spacer and/or a carb heatshield (applies to ALL carbs!), unfortunately about all it does is set the choke! Let me explain.
Typically on engine shut down, much of the fuel in the carb bowl is evaporated due to heat soak from the exhaust directly beneath the carb plenum. That means there is not enough fuel remaining in the bowl and/or accelerator pump to prime the intake plenum properly when depressing the accelerator to "set" the choke.
If you're experiencing this problem, first correct the intake to carb stack-up if you're not using both phenolic spacer and heat shield. Trust me, Opel would not use these unless absolutely necessary (GM bean counters, remember?). In view of this, let me recommend a slightly different starting method for you.
Crank engine half a dozen times BEFORE depressing accelerator pedal to set choke and prime intake plenum. Pump will replenish fuel in carb bowl while cranking and then accelerator pump will be more likely to squirt some fuel into the plenum while setting the choke. TMO.
BTW and FYI, I don't have any "cold start" problems with my completely stock '69 Kadett with joined manifolds and Solex carb using the generally accepted and normally used "press accelerator pedal twice and then start engine" method.
