Can't prime fuel system Rocky Diesel

[Kmac Rocky]

Can't get hold of workshop manual for '89 Rocky Turbo diesel.
Can any one help with following?

Went to start up - never been problems, would not fire up. Hand priming (de-airator) not possible to get any oil out of air vent. Later found with 3psi air into fuel tank diesel would come out of air vent. However, when hand pumping could not get hand priming pump to pull fuel up. Found that putting air in the reverse path air bubbling back to fuel tank.
My logic says, given that there is not actually a mechanical lift pump in the system, that there must be a defective check valve in the pick up pipe in the fuel tank (otherwise the fuel would just drain back from the filter).
Can anyone give me first hand fact on this problem? Any advice would be much appreciated. Kmac Rocky

[jg1982]

Can't get hold of workshop manual for '89 Rocky Turbo diesel.
Can any one help with following?


For a manual: Daihatsu - Worldwide Association of Rocky, Feroza, and Sportrak - Daihatsu Service Manuals (http://www.warfs.org/content/view/16/47/)

[Peter @ Aawen4x4]

If you can pressurise the fuel tank and get fuel out of the bleed vent on the hand primer, but you can't use the hand primer to pull fuel up from the tank end, it's a pretty good bet that you've got a rupture in the diaphragm of the primer pump, so the injector pump will be sucking air not fuel, hence no go!

Just to confirm this, or possibly to get the car going again, you can try the following. Do the tank pressurise thing, and when you actually get fuel coming out of the bleed vent on the primer pump, close it immediately (while it is still running fuel out) then try pumping the hand primer again. Does it get harder to pump? If it does, then you should be able to crack the bleed on the injector pump and pump away on the primer, and with any luck you'll eventually get fuel out of that next bleed too! BUT if that hand primer diaphragm really IS cactus that isn't gonna happen, even tho you KNOW that you've got fuel as far as the primer pump!

Even so, it might be worthwhile trying to get the pressurised fuel tank to push fuel as far as the injector pump bleed, and if you can get fuel out of that, close it off, then try starting the car. That will only work if there is enough suction in the injector pump to overcome the leak from the primer pump, and you should trdat it as an emergency only solution! I wouldn't go running it too far or too long like that, you don't really want to have air bubbles going thru the injector pump while the car is running, and if you do drive it anywhere and you DO hafta stop anywhere, the only way you'll get started again is to pressurise the fuel tank and bleed the system once more!! Still, you aren't likely to get it started if the primer pump is sucking air! It's repair time for that before you go anywhere!

Cheers!

[stu050]

Another thing to check would be the condition of the fuel delivery lines coming from the tank. If these are cracked or perished, it could be letting in air to the system.

If there has been no problems up until now, this is the first thing that I would check.


HTH

[dakar61]

Your reasoning was on the money with the check valve theory, I reckon, Kmac.

I`d bet that that is a lump of crap caught in or the spring broken on one of the prime pump valves in the filter head.

If its dirt you can sometimes dislodge it with a little air pressure or if you give the prime button a couple of good thumps with the heel of your palm while trying to prime the filter, this can dislodge any rubbish caught in the valve, too. The valves arent really accessable, so if the problem persists you may have to replace the assembly.

If the diaphragm was ruptured, as Peter mentioned, it would have been gushing fuel out from around the stem of the prime button each time you pumped it. Fuel would have also blown out of there when you pressurized the tank. Was it doing this?

[Peter @ Aawen4x4]

......... it would have been gushing fuel out from around the stem of the prime button each time you pumped it. Fuel would have also blown out of there when you pressurized the tank. Was it doing this?

I thought of that, dakar, but it would only do that if there was ALREADY fuel in the lines all the way up to the primer pump. And if the car had sucked fuel & air out of the line as it stopped last time, there would be no fuel at the primer pump, so no gushing fuel! There certainly wouldn't be any fuel in the lines after blowing air back into the tank to hear the bubbles! And if you had the bleed valve open when you put that massive 3psi air pressure in the tank, fuel an't gonna come out of anything except the easiest place, and that'd be the open bleed valve, and he said it doesn't do that! So I thought that would probably exclude any check valve issues; besides, I think that along with many other diesels, the Rocky check valve is actually in the primer pump to keep fuel in the line between it and the injector pump - not positive, just a vague thought from days gone by when I was playing with Rocky's at work! The Rocky primer pumps were more bother than it was worth to repair too, way too fiddly; it was cheaper to replace them than pull them apart!

But still, we shouldn't discount any other possibilities, which is why I suggested trying those couple of things to confirm - any different results would point somewhere other than a cactus diaphragm. Besides, we had more than just a few Rocky Diesels with blown diaphragms present with these same symptoms back in those days gone by when I played with Rocky's, it was a redognised problem with them, so i'd think worth a look given the symptoms! Probly wrong tho, cos you'd hope that diaphragm materials would have been changed to be more robust in the intervening years, but you never know.....

Anyhow, it's up to Kmac to try all the suggestions out now, and see if anything presents itself as a solution or suggests exactly what the underlying problem is, innit?! And he's now got a few possibilities to look for, which I guess is why he asked! :D

Any luck yet Kmac? :confused:

[Renasc]

This might not be the way you'd want to go about it, but... my brother was recently having trouble priming is Rodeo (98, 2.8TD). After alot of fussing about, pumping the crap out of the water seperator, he eventually asked his friends father who is a diesel fitter to come and see what he could do. He put one of those squeezy hand pumps (like you'd see on a boat's fuel line) just before the water seperator. Worked a treat.