My latest project. I bought Car Diagnostic Software and an ELM327 OBDII Interface lead to carry out checks on my FL1. My suspicions were that one or more of the fuel injectors were not functioning correctly. Basically, starting and tick-over could be a bit lumpy, especially when cold.
Anyway, I used the Diagnostics and found there were no Fault Codes and everything seemed to be normal. However, I still wasn’t convinced. My reasoning for not being entirely satisfied is because I used Diagnostics on Aircraft, and you only get a part of a much wider picture from the testing equipment. That’s experience. It cannot be taught & we must never assume.
I then formulated an idea, a theory based on fuel consumption and the return of unused fuel to the tank. If all injectors are working equally, then the fuel used should be the same, and the return supply should also be the same for each cylinder. But how to test without a Flow-meter? Hmmm.
I recently replaced the plastic fuel return pipes and connections on top of each injector with Mercedes Brass units. This left me with the original plastic parts. I never throw anything away.
I used 6mm (outer-diameter, 4mm inside diameter) plastic tubing. I bought a roll of this from a pet-shop as it’s used for fish-tank pumps. See Photo No1.
The tubing was connected to each of the four plastic connectors, with three blanked off on their outlets. See Photo No2.
With the engine at working temperature, the overhead plastic cover was
removed for access, I disconnected the Brass fuel return system before connecting my adapted plastic units. Each of the four hoses was fed into four plastic bottles, where any return could be measured & compared following an engine run.
Each bottle should be the same as the others, and any difference would show, by comparison, which was not working properly.
Before running the test I bent the car’s return fuel pipe to block any leakage, tightening it with a tywrap, just like the tubes I was using to feed fuel into the bottles. See photo No2 - again.
With everything fitted and bottles sighted, the test began.
I ran the car for about three minutes, watching to make sure all was well. It was. The return fuel flow wasn’t very much, but enough to show there was indeed a difference. See Photo No7.
Bottles 1,3 &4 were very much equal, but No2 was about twice as much as the others, which of course means only half as efficient. Guess which Injector is getting replaced?
So there you have it. This has proved to be a reasonably simple method of checking your Injectors. And even if you do not have an additional set of fuel return unions, you can still use the ones fitted by disconnecting them and fitting to the type of hose I used.
Information…
The pipe lengths were cut to 100cm’s. The size has already been mentioned. The bottles were used for water, so are oil-based plastic. The collected diesel was decanted into a nylon bottle, saved for cleaning dirty parts.
I hope this might be of some help to others. Oh, it can probably be used on any other type of vehicle too.
Anyway, I used the Diagnostics and found there were no Fault Codes and everything seemed to be normal. However, I still wasn’t convinced. My reasoning for not being entirely satisfied is because I used Diagnostics on Aircraft, and you only get a part of a much wider picture from the testing equipment. That’s experience. It cannot be taught & we must never assume.
I then formulated an idea, a theory based on fuel consumption and the return of unused fuel to the tank. If all injectors are working equally, then the fuel used should be the same, and the return supply should also be the same for each cylinder. But how to test without a Flow-meter? Hmmm.
I recently replaced the plastic fuel return pipes and connections on top of each injector with Mercedes Brass units. This left me with the original plastic parts. I never throw anything away.
I used 6mm (outer-diameter, 4mm inside diameter) plastic tubing. I bought a roll of this from a pet-shop as it’s used for fish-tank pumps. See Photo No1.
The tubing was connected to each of the four plastic connectors, with three blanked off on their outlets. See Photo No2.
With the engine at working temperature, the overhead plastic cover was
removed for access, I disconnected the Brass fuel return system before connecting my adapted plastic units. Each of the four hoses was fed into four plastic bottles, where any return could be measured & compared following an engine run.Each bottle should be the same as the others, and any difference would show, by comparison, which was not working properly.
Before running the test I bent the car’s return fuel pipe to block any leakage, tightening it with a tywrap, just like the tubes I was using to feed fuel into the bottles. See photo No2 - again.
With everything fitted and bottles sighted, the test began.
I ran the car for about three minutes, watching to make sure all was well. It was. The return fuel flow wasn’t very much, but enough to show there was indeed a difference. See Photo No7.
Bottles 1,3 &4 were very much equal, but No2 was about twice as much as the others, which of course means only half as efficient. Guess which Injector is getting replaced?
So there you have it. This has proved to be a reasonably simple method of checking your Injectors. And even if you do not have an additional set of fuel return unions, you can still use the ones fitted by disconnecting them and fitting to the type of hose I used.
Information…
The pipe lengths were cut to 100cm’s. The size has already been mentioned. The bottles were used for water, so are oil-based plastic. The collected diesel was decanted into a nylon bottle, saved for cleaning dirty parts.
I hope this might be of some help to others. Oh, it can probably be used on any other type of vehicle too.
