Fuel Leak-PRV to Tank Connection

[Ragtag]

Big day today, finally managed to dig the 6 out of storage where it has been for about 3 years.

 

Went through the various procedures for re starting after a long lay off, as its about 6 months since last run. Plugs out, lubricate bores, hand crank for a few cycles then turn over on the starter (fuel pump disconnected) to get oil pressure then replace plugs and reconnect fuel pump.

 

At this point I added fresh fuel to the small residual amount left in the tank and keyed the ignition. Old screechy (fuel pump) started but then I heard a hissing sound. Went to the boot to investigate and found fuel apparently spraying upwards from the union that connects the PRV back to the tank.

 

I should say at this point that in all my years of ownership, I've never had a problem with the PI so I'm not that familiar with the set up. If something works, I leave it alone, apart from things that need routine maintenance.

 

So the inevitable questions.

 

The union seems to be like an enlarged brake pipe union but the threaded portion still has threads showing. Is it a taper thread? Does the pipe part of the union extend down into the tank or is it a compressed nipple in the boss on the tank. I should state that I did put a spanner on the union and it wasn't loose but I didn't try to undo it.

 

Finally, any thoughts on why the fuel should be defying gravity and spraying upwards?

 

Thanks in anticipation...........

[astontr6]

Ragtag,

 

There are 2 tapers, one male and one female. The threads are not taper type, the sealing is done on the tapers. These have to be clean and smooth? Are they? Another thing that come to my mind is that the male brass nipple was not properly silver solded or brazed on to the mild steel pipe stub? But has taken 40 years to fail?

 

Bruce.

[Ragtag]

Hi Bruce,

 

Thanks for responding. I have no reason to doubt the threads as the union is not loose and it hasn't leaked until now. I'm a bit surprised that you suggest the mild steel stub is soldered to the threaded male as that would make it pretty tricky to do up and undo the union with the rubber hose connected.

 

On the subject of the hose, I don't have any clips on the hose to stub connection. Is that normal? I'm assuming that the fuel is being sent to the tank at a fair old pressure although I guess it isn't supposed to be meeting much resistance to the flow.

 

I think I'll just attempt to free off the union and see if there is anything obvious.

 

Cheers

 

Chris

[astontr6]

Ragtag,

 

The hose was always just a push fit, quite surprising really. I think that you have misunderstood me? regarding the M/S stub pipe. On the other end of where the rubber pipe is a push fit if the nut is unscrewed off the PRV you will find a brass nipple soldered on to that bit of M/S pipe. This is where I thought it was leaking after reading your thread? Is this correct?

 

Bruce.

[Peter Cobbold]

Surely it should not make a hissing spray - unless the hose has blocked, maybe collapsed out of sight at the top of the tank. An 18 inch column of fuel wont make much pressure at all. At tick over the entire output of the pump , bar a few horsepowers worth, goes back up that hose. If its blocked.... it will spray bigtime. If its open, lots of flow but b888r all pressure. I think its blocked- maybe rust in the top metal pipe.

Peter

Edited April 24, 2017 by Peter Cobbold

[Ragtag]

Thanks again for the responses.

 

Bruce, no, I obviously wasn't clear in my description. The PRV end of the hose is fine, its the other end where there is a 90 degree steel pipe and this is screwed into a threaded boss on the top of the fuel tank. With the pump pumping but the engine not started, fuel is spraying vertically from that union upwards and hitting the underside of the rear deck.

 

I think Peter is correct, in this scenario, there is no demand from the MU so the PRV is diverting the vast majority of the pump output back to the tank and for some reason, this is overcoming the integrity of the pipe to tank union. A rust flake may be the answer but unfortunately, I haven't been able to undo the union for a looksee.

 

The threaded male is brass and my 1/2" open ended spanner (Snap On) is not a tight enough fit to prevent rounding the points and a 12mm is too small. I need to get hold of a 1/2" Flare Nut spanner for maximum grip. In the meantime I've plus gassed the joint and will leave for 24hrs to do its stuff.

[astontr6]

Ragtag,

 

Thanks for that info! On the PI system one must remember that some of the threads are JIC and some are BSP? JiC requires an A/F spanner and BSP requires a Whitworth spanner? I cannot remember what fits those brass taper nuts on the top of the tank. But its not unknown for the brass olives to split?

 

Bruce.

[Ragtag]

Thanks Bruce,

 

I think its 1/2" but just the extra grip of 5&1/2 sides rather than 2!!!

 

I'm not sure about BSP but I think they use Whitworth jaw sizes. If so, 3/16 Whitworth is too small and 1/4Whitworth too big.

[Peter Cobbold]

Thanks again for the responses.

 

Bruce, no, I obviously wasn't clear in my description. The PRV end of the hose is fine, its the other end where there is a 90 degree steel pipe and this is screwed into a threaded boss on the top of the fuel tank. With the pump pumping but the engine not started, fuel is spraying vertically from that union upwards and hitting the underside of the rear deck.

 

I think Peter is correct, in this scenario, there is no demand from the MU so the PRV is diverting the vast majority of the pump output back to the tank and for some reason, this is overcoming the integrity of the pipe to tank union. A rust flake may be the answer but unfortunately, I haven't been able to undo the union for a looksee.

 

The threaded male is brass and my 1/2" open ended spanner (Snap On) is not a tight enough fit to prevent rounding the points and a 12mm is too small. I need to get hold of a 1/2" Flare Nut spanner for maximum grip. In the meantime I've plus gassed the joint and will leave for 24hrs to do its stuff.

Chris,

Lucky you heard the hiss.

I think the PRV return pipe goes deeper into the tank than the MU return, but I'm not certain. Might be tricky to lift it out with tank insitu.

Peter

[HSM]

The union on the top of the tank from the PRV return is 1/2" AF, flare nut

spanner advised, & will come out with tank in situ.

 

Harvey S.Maitland

[Ragtag]

Thanks Harvey,

 

I didn't think the pipe did go deeper into the tank or it would be unlikely to be back spraying at the joint but to be fair, the schematic in the Brown Bible shows it as if it goes in to about 2/3rds depth.

 

I have remembered that I have a home made flare nut spanner made from an old 6 point ring spanner. I'll have a gentle go with that and if it doesn't feel good I'll order a proper one. It's not the sort of thing you can buy in Halfrauds these days.

[Peter Cobbold]

Bro-in-law had a conversion to Dellortos and the garage left that hose dangling. First sharp bend filled the siphon and couple of gallons of fuel were soon sloshing around the boot. So his was not a short pipe. Maybe it changed with production year.

Peter

Edited April 25, 2017 by Peter Cobbold

[Ragtag]

Update...............and egg on face!

 

I decided to repeat the test in a slightly less 'oh god there's fuel spraying everywhere' panic mode and armed with a bunch of rags to damp things down, have established that although the leak looks like the tank joint, it is actually the rubber hose to steel pipe stub (or an unseen split in the hose) that is leaking.

 

The hose is quite old (I haven't replaced it in 10 years) and more to the point doesn't have any markings on it to indicate it is actually fuel hose. I'm going to put a hose clip on the joint tomorrow and see if that reduces or eliminates the leak but regardless I'm going to replace the hose with new. It's a good opportunity to replace the other low pressure hoses as well as they are at least the same age.

 

I'm just glad this has happened now, rather than out on the open road.

Edited April 25, 2017 by Ragtag

[astontr6]

Ragtag,

 

When you replace any PI flexible hose make sure that you do not use R6 spec. which is sold by most of rhe TR suppliers as it does not meet the requirements to use modern petrol. One of those being you get petrol smells in the boot if you use R6 because the petrol vapour comes through the wall of the hose. My replacement hoses came from the USA and are made by Gates the market leader for ethanol resistant hose meets E85 resistance so our E5 no problem! Obtaining E resistant flexible hose in the UK is still difficult?

 

Bruce.

[Kevo_6]

Ragtag,

 

When you replace any PI flexible hose make sure that you do not use R6 spec. which is sold by most of rhe TR suppliers as it does not meet the requirements to use modern petrol. One of those being you get petrol smells in the boot if you use R6 because the petrol vapour comes through the wall of the hose. My replacement hoses came from the USA and are made by Gates the market leader for ethanol resistant hose meets E85 resistance so our E5 no problem! Obtaining E resistant flexible hose in the UK is still difficult?

 

Bruce.

+1 for the Gates hose.

 

Bruce I sent you a PM regards my gearbox.

[Peter Cobbold]

Even so there shouldn't be any signifcant pressure there, not enough to make a hissing spray.

Peter

[Ragtag]

if you use R6 because the petrol vapour comes through the wall of the hose. My replacement hoses came from the USA and are made by Gates the market leader for ethanol resistant hose meets E85 resistance so our E5 no problem! Obtaining E resistant flexible hose in the UK is still difficult?

 

Hi Bruce,

 

Thanks for the information. You can get Gates R7 hose in the UK from Car Builder Solutions

 

http://www.carbuildersolutions.com/uk/gates-fuel-hose-8mm-516

 

Unfortunately I have already bought hose from a local supplier as I didn't see your post until this evening. The hose I have is ISO7840 Marine fuel hose and is certified as alcohol fuel resistant, having a nylon liner.

[Ragtag]

Even so there shouldn't be any signifcant pressure there, not enough to make a hissing spray.

Peter

Peter,

 

Yes, I agree, the leaking hose is the symptom not the cause. I shall remove the threaded connector anyway and expect to find a blockage, I'm just waiting on delivery of a Flare Nut spanner.

[astontr6]

 

Hi Bruce,

 

Thanks for the information. You can get Gates R7 hose in the UK from Car Builder Solutions

 

http://www.carbuildersolutions.com/uk/gates-fuel-hose-8mm-516

 

Unfortunately I have already bought hose from a local supplier as I didn't see your post until this evening. The hose I have is ISO7840 Marine fuel hose and is certified as alcohol fuel resistant, having a nylon liner.

I have never dealt with this company! I myself to date was unable to find anyone who dealt with Gates Hoses in the UK., its a pity that they do not sell the Gates R9 and R14 products as these 2 spec. hoses are way in excess of the DIN spec. that they sell which is rated at E10 max where as the Gates R9 & R14 are rated at E85 and have the lowest permeation ( petrol vapour) rate through the hose wall on the market.

 

Bruce.

[stuart]

R9 hose is available here. http://www.ebay.co.uk/itm/R9-Fuel-INJECTION-Rubber-Petrol-Hose-Pipe-SAEJ30R9-High-Pressure-Line-Reinforced-/140850656095?var=&hash=item20cb5a735f:m:maXm2MNb-YAZkK6h9PSHfUQ

And here http://www.ebay.co.uk/itm/100-BIO-Fuel-Hose-Petrol-Pipe-Ethanol-Butanol-Methanol-Diesel-Cohline-R9-R6-R10-/251182149018?var=&hash=item3a7b9f6d9a:m:maMS093uMOcKpDlojI3bD6A

 

Stuart.

Edited April 27, 2017 by stuart

[kawedo]

Hello,
MOSS sells the perfect GATES Barricade hoses R9 quality.

 

http://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/fuel-system-induction-controls/fuel-injection/ethanol-proof-fuel-hose-by-gates-40970.html

 

Best regards
Charly

[Waldi]

Very good from Moss, at times we are critical to our suppliers, sometimes for valid reasons, but this shows Moss is aware of issues we have and acts upon.

Waldi

[astontr6]

Hello,

MOSS sells the perfect GATES Barricade hoses R9 quality.

 

http://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/fuel-system-induction-controls/fuel-injection/ethanol-proof-fuel-hose-by-gates-40970.html

 

Best regards

Charly

But the H/P version rated at 225 PSI? Which I got from the USA as their Flexible M/U hose still was R6. I supplied my Gates H/P type to Mocal, Moss's supplier for that hose and they made up one for me.

 

Bruce.

[astontr6]

R9 hose is available here. http://www.ebay.co.uk/itm/R9-Fuel-INJECTION-Rubber-Petrol-Hose-Pipe-SAEJ30R9-High-Pressure-Line-Reinforced-/140850656095?var=&hash=item20cb5a735f:m:maXm2MNb-YAZkK6h9PSHfUQ

And here http://www.ebay.co.uk/itm/100-BIO-Fuel-Hose-Petrol-Pipe-Ethanol-Butanol-Methanol-Diesel-Cohline-R9-R6-R10-/251182149018?var=&hash=item3a7b9f6d9a:m:maMS093uMOcKpDlojI3bD6A

 

Stuart.

Stuart,

 

Under SAE approval rules the hose has to be marked with the manufactures name, pressure rating, date of manufacture etc. not shown or given.

Therefore I would not buy as I would be suspicious of their approval?

 

Bruce.

[macs6]

Hi All;

 

Having renewed fuel returns in J30R9,my boot still stinks fuel.

 

Interested in Gates,but Moss only has 5/16 rated at 50PSI,

 

Would this be ok.

 

Cannot remember sizes,PRV-TANK, MU-TANK, are they differant ie 1/4 & 5/16,car away getting work done.

 

If 1/4 and 50PSI ok,anyone know supplier of Gates in UK.

 

Many Thanks,

 

Malcolm.