International Lancia Forums

In response to a question I received by email about installing an electric fuel pump on a Fulvia to prime the carbs.

In general I don't like an electric fuel pump on a Fulvia. Several reasons.

The mechanical pump is simpel, quite capable of doing the job and it gives the right pressure (0,35 bar) for the Solexes. Dellorto's will also run fine on this pressure although some say they like a bit lower pressure better. I have measured several different pumps on different Fulvia's and the pressure was exactly right on al of them and remained constant over the rev range. After almost 40 years many Fulvia's still run on their original mechanical fuel pumps. Name me one electrical fuel pump which has the same reliability.

If priming takes too long, there might be another cause such as dirty fuel filters or fuel lines or dirt in the fuel pump. My Fulvia's hardly take longer than 20 seconds of priming after many weeks of not being used. Installing an electric pump may mask potential problems such as completely blocked fuels lines / filters, bad starter motor, insufficiently charged battery, voltage regulator going bad. Better fix these potential problems first and then think again.

The disadvantages of an electric fuel pump are:
- it continues pumping after an accident if the engine is not switched off
- it draws current and thus reduces range in case of a dynamo / alternator failure.
- it unnecessarily loads V-belt, pulleys and dynamo / alternator
- it may flood carbs

A simpel device for priming the carbs is a handpump as used with outboard engines. It looks like a rubber ball and is connected in the fuel line. Squeeze the ball a couple fo times before turning the key. You have to open the bonnet anyway to check oil and water.

If you still want an electric pump, then connect it in parallel with the mechanical pump using T-pieces and operate it through a switch on the dashboard. Feed the switch from the "yellow circuit" which carries 12 volts when the key is turned 90 degrees (and 180 degrees). Switch off the pump when the engine runs. Since I often forget to turn off switches, I would connect it to the same wire that operates the startermotor. It will take a bit longer to prime the carbs than when operated through a seperate switch but it is safer.

Huib -
While I agree with you in theory, in practice, I enjoy having the elec fuel pump. I use a spare switch on the dash to turn it off while running and only use it to prime the carbs.

The biggest problem I have had with the older Lancias has been the fuel draining and empty float bowls. I suppose a one-way valve might help the draining back, but not necessarily the empty float bowls. The use of the pump to prime the carbs reduces wear on the starter motor especially. On my Appia C10 we have not mounted an elec pump (as the car is so dead original) but it takes some real time to primethe carbs. typically more than the 20 seconds. Some starter fluid helps, but is not a good long term solution.

Overall, I'd recommend the elec pump, if for no other reason than to spare the starter. Turning it off while the car is running with a separate switch gives the driver the option if they find they need it.

Geoff

Everybody is of course entitled to do as he or she likes. Many people are happy with an electric pump, either as a replacement for the mechanical pump or as an auxiliary pump to prime the carbs. Let's say I am playing the devil's advocate by mentioning some disadvantages often overlooked.

My Appia also took a minute to prime the carbs. Some years ago when participating in a sliding pillar rally in Luxembourg the engine stalled. After cleaning the fuel pump it went for another few kilometers and stalled again. After several repeats I finally called for the trailer. Fortunately we found a workshop willing to help us on saturday evening. The fuel line was blocked solid. At first we could not even get the dirt out with compressed air. After removing the drain plug from the tank we finally got the dirt out by blowing compressed air alternatively from front to rear and rear to front.
The filter in the tank had holes in it.

When at home I repeated the cleaning, installed a new fuel pump, overhauled starter motor and dynamo and put a new voltage regulator. Now it starts within 20 seconds. I had already bought an electric fuel pump for the Appia but had not yet installed it. And I never did as I concluded that the time to start the engine is a good way of early diagnosing a pending problem.

You mention fuel draining. I suppose you mean that the fuel flows back into the tank. There is a one way valve already in the system. In fact there are two. Both are in the fuel pump. The fuel pump works on the same principle as a bellow to inflate air mattresses. It has two small flexible valves. Chances are these are not properly closing anymore either because of dirt particles stuck in there or deformation and hardening of the valves. Better fix the fuel pump as this is an early sign of failure rather than inserting an extra valve.

Really, the hand pump as used on outboard engines is the ideal device to prime the carbs. It is small, cheap, very easy to install and leaves everything original except that you have to cut a fuel hose to insert the pump. If one is methodical (I am not. I am chaotic) it also has the possibility of early diagnosing a pending fuel supply problem. One could establish how many squeezes it minimally needs to prime the carbs sufficiently to start the engine at first spark. If some time in the future it does not start at first spark with the same number of squeezes but still needs some time cranking the engine with the starter motor it is time to search for a cause and prevent being left at the side of the road.

If the valves in the fuel pump are leaking, efficiency of the pump has been reduced which adds to the time to prime the carbs.

It is no doubt true that cranking the engine with the starter motor results in extra wear of the starter motor.
I am not sure what causes the wear on the pinion. Is it at the time it engages? Or also when turning the flywheel? If most of the wear is at the time it engages the teeth on the flywheel (which also wear) a solution is to continue cranking till the engine starts rather than cranking with intervals. In that case there is no difference in number of times of engagement between having an auxiliary electric pump or not.

While wear on the starter motor is a negative point, a positive point is that while turning the engine, oil is pumped around in the engine. If the fuel has gone from the carb, I would assume that oil has also gone from most places.

Above a picture of a fuel hand pump as used for outboard engines. This is a high quality one from Yamaha. Costs about 20 euro.