Giving the New Engine What it Needs!

Diesels aren't typically very needy (older ones anyway) when it comes to outside connections. Most will run with just:

Fuel send line (from tank)
Fuel return line (to tank)
+12v to diesel solenoid (not always a neccessity)
Battery negative wire to the block
Positive wire to the starter
+12v to starter solenoid

My Volvo has mechanical stop control rather than a solenoid, so its just the other five!

The boat came with the fuel tank pictured, and all the framing is the for it to fit snugly under the port berth. It has a couple of downsides however. The first is that it only holds around 30 litres, which is only an hour and twenty mins or so at cruising fuel consumption (calculated at 70hp). The second is that it has no baffles.

Baffles are internal plates inside a fuel tank designed to stop fuel sloshing around, which its prone to do both during changes of pitch or roll, and changes in direction. With a petrol engine this is less of a problem, because the fuel tank pickup can suck up a bit of air from time to time, and this will escape from the vent in the top of the carburettor. With a diesel however, the injectors need hundreds of PSI of pressure to open and squirt fuel into the cylinders, which is supplied by the injector pump. If air gets into these high pressure injection lines, it acts as a cushion, since it is compressible, whereas diesel is not. The cushioning effect means the pressure in the injector lines drops and the injectors don't have enough pressure to open, and the engine stops running. It won't run again until the injector lines have been bled of this air, which is a time-consuming and sometimes difficult process. Hence baffles are a good thing!

Anyway, thats of small concern until we're actually close to boating, so we'll focus on the neccessities. First, a send line must be run from the fuel tank to the fuel inlet of the diesel filter housing. This was made from 6mm ID copper, flared to fit the tank fitting and connected with hose to the filter at the other end. A return line was also made from the same tubing, which takes excess diesel (used to cool the injectors) back to the tank.

Since the tank was designed as a petrol tank, it has no return fitting. In the photo above you can make out the return fitting I made, from an elbow of steel fuel line (has a hose attached in photo), glued with epoxy into the tank. Epoxy has good resistance to diesel (and many other things) plus a high mechanical strength, so it made sense to make the fitting this way. With that taken care of, it was just electrical matters to take care of. Or was it (spoiler alert)?

I then put battery terminals on some heavy gauge wire I took from the SR20. The negative was connected to ground, and the positive to the non-live copper bolt connection on the starter motor solenoid. I put an alligator clipped wire on the solenoid trigger, so that when the other end was touched on the +ve terminal, the engine would crank.

I'd half bled the diesel send with an old primer bulb, and expected it to fire up without too much difficulty. I pulled up my car alongside with jumper cables to the batt expecting to have to crank it for a bit to get diesel through everywhere it needed to be.

After several minutes of glowing and cranking on and off (ah forgot to mention, the other connection needed is lots of amps to the glow plugs, done here with a jumper lead from the battery) there was no sign of life. I tried all kinds of things; checked and cleaned the glow plugs, tried some WD40 in the intake, tried running the primer bulb in-line and bleeding that way, cranking with injector lines off till diesel came out, but nothing worked.

Sexy primer bulb can be seen here, at the front of the motor

The next day I got it going briefly, but it couldn't manage more than 30 seconds at a time. I noticed the feed pump pictured in the manual hadn't been supplied, so suspected that it needed one. Knowing that some cars had 'lift' pumps, I thought I'd have a look around a junkyard.

After many hours of sweaty, grimy junkyard perusing with no success in finding such a pump, I thought I'd try a better quality primer bulb with nicer check valves. For $25 it was worth taking a chance on, as it'd be an easy fix if that was in fact the problem. After bleeding at the filter, injector pump and the injectors it started after 15 seconds of cranking, and has since run fine. THANK GOD.