Diesel Mark 7 Ford fitting fuel filter sucking air

[collins75s3c]

Hi Everyone,

Well, I bought the Mark 7 with the 2.4 l BMW Diesel engine to learn something.
The learning curve has been very steep. When I got the car with 77,000 miles
on it, it came with a long crank time for starting. After wearing out a starter and
replacing it, it would start a little better in the warm summer weather. Then it got cold.
Even with the block heater plugged in, long crank to start. Something had to be causing
this, so I unplugged the glowplugs from the glowplug timing module on the firewall.
Four out of the 6 glowplugs measured open. Ah ha, this could be my problem. I had already
purchased a set of American made plugs from DieselRX. Replacing the glow plugs and using
copper anti seize (per the Ford Shop manual), with a bit more confidence, cycled the glow-
plugs and cranked the engine. Same long crank. Clearly, there was more than one problem.
After a long crank with the engine running I stuck a spacer in the injection pump to increase
engine idle speed. The engine revved up and quit. Suspicious that it wasn’t getting fuel, I pur-
chases a new electric lift pump. Unlike the BMW that used a pump in the tank to push the
fuel to the injection pump, the Lincoln version sucks the fuel using the electric lift pump.
FFrom a YouTube video, I decided to suck the fuel using some clear hose, fittings, and a hand
vacuum pump, I discovered some diesel fuel and mostly air! No wonder it wouln’t start or
perform very well. The source of the air was traced to a right angle Ford push on fitting
on a piece of 3/8 brass pipe. So off I went to get a new fitting. Fitting installed, I used the
clear fuel line going through the electric lift pump to check for air leaks. Worse than the
original Ford fitting! Removing the fitting and gently curving the fuel line, I pushed the line
on the brass pipe and secured it with a spring clamp. This time I got solid diesel fuel with no
air bubbles. Putting everything back together and connecting to the injection pump, a quick
glowplug cycle and the engine started within a few seconds of crank. The next morning with
the block heater was plugged in it started right up. I should have known. If this had been
a gas engine that I have worked on for years. I would have what to do. While the diesel
engine needs the same thing as a gas engine does, my lack of familiarity with diesel
clouded my thinking. As a final note, sometimes the simplest problems are the hardest to
solve. Lesson well learned. Collins75s3c
PS The previous owner claimed the car had Bosch glow plugs. 1 was Bosch and the others
were Champion. Hmmmm....

[gadget73]

Welcome fellow Lincoln owner.

I had the same problem with those stupid quick connect fuel fittings. One had been deleted and the hose just clamped to the fitting. The one between the filter and the lift pump was still there though. I replaced that fitting with an M14 to barb fitting and just installed a new piece of hose between the filter and the pump. Its starting to do it again after sitting a week, and I suspect its the one I didn't touch. It starts, runs smooth for 10-15 seconds, then either stalls or nearly stalls. If I keep it running with throttle the problem clears and then it runs fine again. I'm pretty sure the fitting on the tank side is the original quick connect bit with the hose simply stuffed on and clamped.

I did consider re-arranging the fuel system so the pump wasn't sucking through the filter, not sure if that would get me anywhere useful or not. Not really motivated to modify things enough to put a lift pump in the tank.

and yeah it is a bit of a learning curve for sure.

[gadget73]

My own air problem came back and I finally found it. The rubber feed line between the line on the chassis and the filter was cracked at the filter end. Not enough hose to cut and re-land it so it needed new line. To my surprise, I found another of those quick connect fittings down at the connection to the steel line where it ends underneath of the fuel filter assembly. I re-installed it after rebuilding the fitting with new O rings and a new length of rubber hose. Fair warning, if you unhook this line the tank will gravity-drain diesel fuel. I found this out when I got back from the parts store to find a small lake of fuel in my garage. The fitting could be eliminated but you'd probably need to get under the car to do it. I was working topside and was able to get the hairpin retaining clip out and back in once I unbolted and moved the fuel filter housing out of the way.

[collins75s3c]

Diesel Mark 7 Ford fittng sucking air follow up
Hi Everyone,
One of my favorite sayings you are never to old to learn something new. In my original
post, it was true that the Ford right angle fitting going to the electric lift pump was
sucking air. While it was true that the fitting was sucking air, causing the diesel to
have long cranks and hard starting, I did not realize the real reason for the fitting
sucking air was improper installation by the previous owner. To make a long story
short, when I eliminated the right angle hair clip fitting and shoved the fuel line
on with a spring clamp, the raised 'flange" would cause a leak if the hose was distur-
bed. The fuel fitting and how to install it is covered very well in the Lincoln Supplement
manual for the BMW diesel engine. One is to push the fitting on the brass line over
the flange until a distinct click is felt. Then insert the nylon clip and you are done!
I purchased new fittings and restored the fuel lines and fittings to factory original.
The diesel started right up with a glub-glub in the tank which was the air bleeding
out of the system. The Mark VII diesel runs better that it ever has. My thanks to gadget73
for his reply to my call for help and his advice. It was very much appreciated.
Happy dieseling everyone!

[gadget73]

cool, glad you got it worked out. I do not love those fittings. I've got them on my 86 Towncar, the 84 Conti and the 91 Mark VII. The gas cars use them at the fuel filter. Extra fun points if the O-ring tears changing the filter. Gas sprays out of there at 40-odd psi. Luckily they can usually be fixed with new O-rings but laying under the car while its dripping gasoline in your face to do the job is not any fun.