It was a FUEL HOSE

[philip]

Sometimes it's the LITTLE things that drive you to drink.

Symptoms: The hotter the engine got (speaking to underhood temps), the shorter the time at idle before the engine would start misfiring. With the misfire established, it would clear up with one throttle blip ... for about 30-60 seconds. Cracking each injector line with the misfire present, cylinder #1 always expelled air. Hmmm.

Last night I was under the hood ... and noticed a very high pitched "wheezing" coming from somewhere. Then it went away. I ran the engine for awhile and then shut it down. The "wheezing" sound was audible again and now louder. I listened around REAL carfully and ... I FINALLY sourced it!



This is the last inch of fuel hose on the primary filter (suction side to fuel pump). This TINY hole next to the OEM wire hose clamp was admitting air! The "through point" on the inside is evident with a magnifying glass and focused light. I replaced all these hoses about 18 months ago!

Trimmed it off. No more "wheezing" and no more symptoms.

[kassim503]

that is the worst

[philip]

Regarding the replacement of all SIX under-hood rubber flex lines on SDxx equipped with the "inline" injection pump in Datsun/Nissan pickups. There are two more short sections of hose back at the fuel tank.

1) The two lines going TO and FROM the little Primary filter are 8mm (5/16") in diameter and about 21" long.

2) The two lines going TO and FROM the injection pump are 6.3mm (1/4") in diameter and about 16" long.

3) The single return line leavng the "OFV" fitting on the Secondary filter is 8mm (5/16") and about 21" long.

4) The small single return line leaving #4 injector is (3/16") and about 22" long.

I highly suggest getting diesel fuel specific hose for positions #1 and #2 as #1 is subject to some vacuum while #2 is subject to about 20 psi working pressure.

Yeah diesel fuel line costs more (est $1.50 per foot) but there is little danger of the inner liner disintegrating in a short time when you run a biodiesel blend (ie, B20).

There is another thread devoted to B100 fuel lines.

YELLOW: Suction lines
ORANGE: Low pressure delivery to secondary filter
RED: Low pressure delivery to injection pump
GREEN: Dribble return lines back to fuel tank

[Zoltan]

Here's my answer (to my fuel line question on a different thread) !!! What are the diesel spec. fuel lines made of ? The only car parts stores we have in Hawaii are NAPA, Checkers and a few Carquests and they do not cater to diesel owners. I'd probably have more luck with a hardware store...

[philip]

Here's my answer (to my fuel line question on a different thread) !!! What are the diesel spec. fuel lines made of ? The only car parts stores we have in Hawaii are NAPA, Checkers and a few Carquests and they do not cater to diesel owners. I'd probably have more luck with a hardware store...

Well as you can see, generic gasoline hose is not suitable for diesel particularly when B20 biodiesel is used on occasion. This hose would probably dissolve within weeks with B100 use.

At the moment, I am experimenting with fuel line. For the two suction lines servicing the little primary filter (5/16"), I am trying rubber lines designated for "automatic transmission cooler" use (NAPA). For the two lightly pressurized lines servicing the fuel injection pump (1/4"), I am using diesel fuel specific line. I cannot say just what this hose is made from but ... the hose is definitly two different layers (blue outside, white inside) with woven reinforcement in the outter layer. The inner layer is shiny, smooth, and looks like some sort of vinyl mix. The pedigree inked on the hose reads: LDL Plus 4LOLB+ 1/4 inch 300 psi WP Flame Resistant Covering Made In USA GL110101 23044. A Gates Hose .pdf has this description:
Recommended For: Petroleum-base hydraulic oils, antifreeze solutions,
water, hot lubricating oils, diesel fuels and air. Lock-On hose and
couplings are not recommended for vibration or pressure surge
applications or for critical applications, such as permanent piping in
residential or commercial buildings.
Tube: Black, oil resistant synthetic rubber highly resistant to oil and heat.
Reinforcement: One fiber braid.
Cover: Oil and abrasion resistant synthetic rubber.
Colors: Red and Blue

This diesel specific ("flame resistant") hose I purchased from a commercial diesel truck repair supply store ($1.65 per foot). NO auto parts store in Orange County had designated diesel fuel line. It was available only in 1/4" diameter (which is the diameter needed on the two injection pump lines). And no matter what, DO be SURE to get double banded clamps ... ones that cannot bite into the hose's outter surface. NAPA has these better quality clamps. See Al's thread on fuel hoses for biodiesel for an example of this kind of clamp. There is also a double banded worm gear clamp design which is what I use.

[philip]

With a modification to the fuel system designed to enhance air purging, the additional flow revealed another air leak on the suction line that feeds the lift pump.

There is a 10" length of (original) rubber hose on the suction line at the fuel tank. This line showed no signs of liquid leaking out but ... its replacement fixed the constant stream of bubbles entering the primary filter.

Both ends had deep cracks and these OEM wire clamps.

[asavage]

Were you able to replace those lines without removing the bed or dropping the tank?

I did mine with the tank out (see pictures, top of "Biodiesel fuel line replacement" thread).

[philip]

Were you able to replace those lines without removing the bed or dropping the tank?

I did mine with the tank out (see pictures, top of "Biodiesel fuel line replacement" thread).

Jacked up under the frame so the suspension dropped, replace easily!

[Zoltan]

I am still hunting for biodiesel resistant fuel hoses. I came across Thermoid, it has SAE 30R9 rated hoses in 1/4" and 5/16" size. The part numbers for these fuel injection hoses are: FI-502 and FI-503 (or PI-502 and 503 depending on the order size), but nobody seems to carry them here in HI.

As for the 3/16" size, I could only find SAE 30R7 rated black fuel hose (part#: P501, 25046, 25048, 25049, 25099, 15032).

If you guys know any one who sells these hoses by the foot, please let me know.

[ecomike]

Today I ran across and bought some fuel injector hose. I found three stock sizes of fluoropolymer hose on the shelf at the local Pep Boys store. It has a thin flouropolymer liner on the inside diameter, special braided reinforcement middle layer, good to 100 psi (500 psi burst), with a Hypalon (technical name Epichlorohydrin) outer covers good to -30 F and +300 F. It came in 18" lengths packed in a plastic display pack, $4.49 to 6.49 a box depending on the diameter. They had:

Dayco part #80078, 1/4" (6.4 mm) ID

Dayco part #80079, 5/16", 7.9 mm ID.

Dayco part #80080 (or PD2060, or Life Line #301111, it was older stock with several ID numbers on the box)., 3/8", 10 mm ID.

This stuff should work on the both Vacuum pump oil lines and the fuel pump, fuel tank, and fuel injector lines even with B100 biodiesel.

Also, a few months ago, I found out O'Rieley's sells high pressure fuel injector hose much like this stuff in bulk (thin flouropolymer liner, braided reinforced middle section, with fuel resistant cover, but they get something like 5 to 10 dollars a foot for their stuff, IIRC. This is much better stuff than pure Viton for fuel hose or oil hose as it is reinforced for higher pressures, and makes much tighter bends. And it is available in at least 3 diameters.

[asavage]

It's too bad that we can only buy this stuff in SAE sizes.

How many years has it been since cars in the US used SAE-sized fuel lines?

I complain every time I have to buy fuel line from my FLAPS. Where is the good equivalent for 4mm? Or 7mm? And 3/8" is not a great fit on 10mm, IMO.

Thanks for the update, Mike.

[TruckA]

The Pepboys hose works fine, I've been running it with biodiesel since I finished the swap. The only problem was the hose that runs off the fuel rail going back to the secondary filter. I had a problem where that hose kept bursting out the side near the rail. I ended up putting on a Goodyear type hose that was longer to hopefully lower the pressure in that hose and I haven't had a problem again.

I also went to a diesel shop a while back and bought some really great hose that I have yet to install. I'll have to update what brand and type it is when I can.

[davehoos]

I got a roll of name brand small vac hose to replace the hoses on an old ford.I had to cut several lengths to get a section with the needed ID to get it to fit tight.

for fuel hose when i worked for Landrover they used air brake hose.nylon looking.you heated the ends and pushed it on to steel double flare fitings like found on most japanese systems.olive type fitting also are used on position like the fuel tank that had no flares.SuperGlue [loctite 407?] was used i think to hold in position until cool.

i recently worked on a 60's for cortina and the same deal was used ex factory.
the hose had drooped onto the tail shaft and sealed off.

[ocd]

thats funny i just used the DOT A air brake lines for tractor trailors for the fuel lines on my peugeot.

the saga of "low pressure return lines" popping off and leaking was unending until i realized that the main return(3/8 steel) from the fire wall to the tank must be clogged. confirmed it with 120psi air unable to travel through.

while wandering around the shop trying to figure out what to do, not wanting to spend anymore money on that french b*tch, i found rolls of the stuff and droors of fittings for it.

after researching what it was made of (nylon) and its working/burst pressure(sorry not off the top of my head but substantial) i replaced both the feed and return, checked for leaks and took her out and ran the piss out of her, no leaks, parked her and havn't touched her since(water pump belt falling apart, something flinging oil around -anyone want a french mistress?).

of course that doesn't tell us much but i will check those lines and report. my concern is how it will handle vacuum.

-update- drove fine on several "test drives" till the last when she started giving signs of fuel starvation. i shook the fuel filter -no slosh. no further checks. her next victim was still excited about the car. what a seductress.

[chrwei]

This is much better stuff than pure Viton for fuel hose or oil hose as it is reinforced for higher pressures, and makes much tighter bends. And it is available in at least 3 diameters.

"this" being the pepboys or the o'reilys stuff? or either?