Clear/transparent fuel filter for fuel injection pressures


Quick question here... I'm having to resurrect a large number of cars after some years of slumber. Most are vintage/carbureted cars but a few are newer cars that are fuel injected.

The older/carb cars are fairly easy - soak a bit of magic oil in the bores for a while, git a new lightning box, git some fresh/filtered fuel to the carb, check the carb operation, maybe do a compression check, etc. I'm using a WIX 33003 clear plastic filter ahead of the carb to see what the fuel looks like before letting it into the carb.

The newer cars are a bit (a lot) more complicated. I'm roughly following the same drill, however, I would like to be able to visually see the condition of the fuel by way of a clear fuel filter spec'd for fuel injection pressures. Typical pressure would be 30-70psi. This is mostly Bosch motronic or CIS type injection on 911, 80's Alfa, mercedes, etc.

Anyone know of a good (WIX?) inline clear fuel filter spec'd for these type of fuel injection pressures? 3/8 or 5/16

Sorry if this is in the wrong area - is it? Thank you in advance.

Bill Kearley

Cliff, you should be all right if you can find one with a 2 inch wall thickness. Not sure about all systems but couldn't the filter go on the suction side ?

Ken Roberts

If the fuel injected cars have schrader valves on the fuel rail I would remove the cores and connect a hose to it then pump the fuel into a bucket. You can make an electrical jumper wire and connect it to the fuel pump relay so the fuel pump is running with the engine off.
Yup, exactly, I won't be trusting fuel injection pressure to a clear plastic type fuel filter.....

Unfortunately, no schrader valves. The early motronic and CIS just wasn't that way.

I'll keep looking for some kind of clear/visible fuel filter capable of FI pressures, but like you've suggested that may not be something that's available.

I would disconnect a fuel line and not let the old gas get to the rails. One of the big problems with ethanol enriched fuel is it's hydrophilic and will suck moisture out of the air to the point the alcohol and water fall out of suspension and make a thick gooy semi combustible plob that will stop up the little screen in the injectors and glue them shut.

Do everything you can to get it out. A little bit may redissolve with the cleaners but the less the better.
Use ethanol killer to prevent these issues.
I use Ethomix for more then a decade in all my vehicles and never have issues in my fuel system since.

Working on a Customers 230SL Pagode now who wished he used some ethanol protection. Injectionpump control rod is stuck inside the pump after two years of storage not running. Thats a pretty expensive repair job.