Need advice on biodiesel in a 6.2L

[BIOBEV]

Is anyone using biodiesel in their 6.2L vehicle? I need to know what needs to be changed on my 1988 Suburban, fuel lines, fuel pump, injector pump???? I know biodiesel can damage some parts just don't know which parts. Should I upgrade pumps and if so to which pumps, should I change out all my fuel lines, should I have my tank cleaned out first any advice from someone that actually has done this would be wonderful.
Thanks:confused:

[john8662]

Biodiesel can be run in these rigs as is, but you're right in being worried about the fuel lines.

You will need to replace most of the fuel lines on the vehicle that are rubber with a synthetic hose. Most of the lines on the vehicle are 3/8", 1/4" or 1/8" ID lines.

The fuel return line are 1/8" ID from injector to injector.

Now.. This is coming from someone that isn't running biodiesel, but this is just what I've read.

J

[83Blzr62]

I have been running biodiesel for about a year and have had no problems with the fuel lines. You should replace them with synthetic though because they will eventually deteriorate. I did replace my IP return lines with viton from mcmaster carr. It was kind of expensive, but they will last forever. The fuel pump will be fine and the injection pump seals should already be viton if it was rebuilt lately. If they are still original it would probably be a good time to replace them anyways. You can get the IP rebuilt from accuratediesel.com for pretty cheap.

[BIOBEV]

Thanks for the replies. Blzr6.2 did you clean your fuel tank out before you used the biodiesel? If not did you get a lot of clogged filters for a while? Should I clean my tank to aviod problems?
Thanks

[Subzilla]

To avoid replacing your expensive filters, put a cheapo in-line filter ahead of the regular filter and keep extras in your kit. When you start feeling the engine power taper off, just replace your pre-filter which will probably be filled with all the tank crud. Eventually, this problem will disappear once all the tank and line crud is cleaned out.

[gavio]

When I started using Biodiesel about three years ago, I did not get my tank cleaned at the time and did not have any particular problems with excess gunk so it's not a given that you will have problems - pay attention though, cuz it depends on the history of your truck - be aware also that clogged fuel filters will manifest as a LOT of different symptoms - often things that do not intuitively seem like they would be related to filters. If you've a mind for it, the cheap prefilter idea is a good one, though I haven't done it.

I did replace my fuel hoses because they were old and soft. If yours seem reasonably new and solid, there's a good chance they will last a while with biodiesel, so it may not be an immediate action item - but watch them. Be sure and check the hoses that connect to the tank itself - they are a pain to replace and may still be the originals........

The Viton from Mcmaster Carr, as mentioned above, ROCKS for the return lines - I tried a few things before finding it (info was a bit scarcer back then, and we still walked everywhere barefoot in the snow uphill both ways....). The stuff you want is the softer grade in the metric size that is slightly smaller than the fittings on the injectors measure - the softer stuff has enough give to stretch safely over the ends and has lasted for years now. The harder grade is too stiff and will crack almost immediately (doesn't take a lot of imagination to figure out how I know...)

Ditto Blzr's comment on pumps - if yours still has rubber in it, it probably needs a rebuild by now just because it's a Stanadyne DB-2 - mine started leaking out the throttle shaft with my first tank of biodiesel..... when I put on a fresh one, the difference in performance let me know that it had been overdue anyway. It has not given me trouble since (everytime I have thought I had pump problems since, it has turned out to by my fuel filter - see above......)

Good luck!

[83Blzr62]

I had no gunk come out of the tank that I could notice but i change my fuel filters pretty regularly any ways. I was told on a biodiesel forum that you should change them 500 miles after your first tank of biodiesel and then another 1000 after that and then at regular intervals. Like said earlier, you can feel the car slow when the filters are getting clogged, if you know your car. The inline cheap filter is a good idea also.

[BIOBEV]

Thanks for all of your input. I probably will have the IP rebuilt since the truck has only 70,000 original miles and I doubt the old guy I got it from had it done so I assume the parts in it are still rubber, I will get the fuel lines changed out and use the in line filter method to filter out any junk. Thanks Again!

[john8662]

70k miles on an 88 model pump? I wouldn't worry about changing it! The main pumps that had problems were the early pre ~85 pump with flex rings verses EID's.

You should be fine.

J

[jonflies]

I dropped the tank out of my 82 last fall, and ordered hoses through the mail. The tank has a drain line, a return line, a supply line, a filler line and tank vent line. ALL are different sizes. I found the drain, return and vent line, but had to replace the supply and filler with marine grade or injection line hose, which I hope will last.

This is what I found on mine.

The filler tube is 1.75 ID and 2.25 OD.

The filler vent is 5/8 ID and 7/8 OD.

3/8 ID and 5/8 OD

5/16 ID and 9/16 OD

.25 ID and .5 OD
I ordered some from Greaseworks.

Plan way in advance, it took some time to gather everything. I ended up cutting two holes in the bed of my suburban, so I could verify I didn't have any kinked lines.

My tank was kind of nasty inside, but there's no telling where it came from in a 24 year old truck.