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Warning for all Jeeps with steel fuel tanks


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Despite what Jeep have told the DVSA about E10 compatibility for XJ and YJ, Jeeps fitted with steel fuel tanks are not even compatible with E5. If your Jeep has high pressure rubber fuel hoses (SAE J30 R9) made before plastic tanks were introduced in 1997 models, the fuel hoses are unlikely to be resistant to ethanol blended fuels. Check them for cracking or bulging now. If they do not look in perfect condition, there is a good chance that they are suffering from ethanol corrosion internally.


If you do need to replace your existing hoses with new hose, insist that your supplier accepts your condition of sale that the hoses are money back guaranteed ethanol resistant. This should also include Mopar hoses as the current Jeep brand owners clearly haven't got a clue what the former owners used in the manufacture of older models.


High quality new fuel injection hose that is ethanol resistant is made by CODAN and by Gates. Beware of unbranded hose marked 'W=SAE J30 R9', this is fake hose that fails.


It is my opinion that those of us with steel fuel tank Jeeps should also change the fuel filter every year, or as frequently as you would change an oil filter. Rusting caused inside the tank by phase separation of ethanol blended fuel will end up in the fuel filter. If you are not using your Jeep daily, you should consider adding a fuel stabiliser and corrosion inhibitor at every fill or drain the tank if not being used for a week or more.

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What you do with the drained stale fuel is another problem that the environmental lobby simply overlooked when insisting on ethanol blended petrol. Stale fuel that has experienced phase separation is a lower octane than the retail petrol you bought. If your engine can run on low octane petrol I guess you could put it back in your tank. Otherwise, it may be usable in low octane garden tools or lawn mowers. I have heard of some people adding kerosene or heating oil to the drained petrol to lift the octane for reuse.

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Hi Vince, you have me rather concerned about this ethanol issue.

I was aware that there could be issues, but my Yj runs better on Super any way so I've continued to use that.

However, at Crossgates I was forced to put in E fuel,can't remember which! I still have 3/4 tank left. I have a plastic tank and everything seems ok. Fingers crossed. Draining it is a big issue. It has no drain and is encased in a tough looking steel guard which doesn't look simple to remove plus I still haven't recovered from the weekend yet. I have found stabiliser locally at Toolstation and plan to put it in tomorrow ,then use fuel asap and put super in when its as low as I dare. What do you think?

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I am going to use the same stabiliser from now on, B3C. My older XJ has LPG so I don't keep the petrol tank full and when I do top it up, the petrol is usually in there for months. Both practices are now a recipe for disaster for steel tanks and ethanol blends.


I have been reading about sender unit electrics and mechanicals corroding under galvanic action. For some older cars even the sender floats have been rupturing. I am going to try to restore my steel tank before buying a new replacement.

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  • 3 months later...

My '93 XJ had a 30 mile ride on a transporter back in April when I found that my Jeep had suffered ethanol damage over lockdown. It was sitting still with half a tank full of E5 for months - NOT E10! Today, I pulled the fuel pump and sender unit out. All of the external fuel hoses were internally corroded and very 'mushy' to touch. Surprisingly, the fuel strainer did not look particularly dirty with rust but the in-tank fuel hose had burst and the original equipment pump mounts had dissolved into a soft tar like mess. I had modified my original equipment pump assembly to use a high flow after-market fuel pump in preparation for an engine rebuild a few years ago. The pump is also damaged and barely spins under power.



The in tank fuel pipe has burst. It is very soft and looks like it has been dissolving.



Original top mount for the fuel pump has also suffered ethanol corrosion.



And so too has the original bottom mount for the pump



The in tank rubber parts removed. They were very soft and gooey.


I have a new pump to install but I will have to make some sort of ethanol proof anti-vibration mount as the original pump mounts are useless now. This damage was all caused by E5 petrol bought prior to September 2021. My Jeep primarily runs on LPG so I don't use much petrol and have not put any E10 in it.


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think 1999 TJs dont have steel tanks ?  Also I found my TJ 4.0 doesnt seem to run as smootly on super unleaded as it did on regular

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TJ Wrangler's have plastic tanks and a top mounted submerged fuel pump/sender. As far as I know, they were designed to run on ethanol blends. If your Jeep runs OK on E10, use it. My 2001 XJ loses 1mpg to 2mpg on E10. I change my oxygen sensors fairly regularly (4 to 5 years).

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I have been doing some more research today. Other fuel injection hose that have been proven to be ethanol compatible are:

  • Cohline 2240
  • Continental DIN 73379-3D
  • Goodyear SAE J30R9

There are still lots of fake R9 hoses on eBay and Amazon. Be sure to buy from a reputable stockist that guarantees ethanol compatibility in writing as part of your conditions of sale before you purchase.

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I purchased Cohline 2240 hoses as they are 100% ethanol proof. R9 spec hoses have varying levels of ethanol resistance so you need to check the manufacurer's specification if it is suitable for E10, E15, E25, E85 etc.

I bought my hoses from CohPro. The cost with delivery was under £38 including VAT for the two sizes that I needed.

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  • 3 weeks later...

I installed my freshly modified fuel pump assembly today and replaced the remaining damaged hoses with Cohline hose. The Jeep starts and runs without having to replace any more parts.


I cut open the old fuel filter to see what it had caught. On the dirty side there seems to be some fine dirt deposits on what was the low side of the filter.



The dirty side of the paper element appears to have caught a lot of black particles. This could be the dissolved rubber components that were in the tank and the hoses up to the filter.



The clean side is still relatively clean with no sign of the black particles making it all the way through in large concentration. The good thing is that the filter paper is not rust stained which means the inside of my steel tank is not rusty. I decided to take a chance on the fuel regulator and fuel injectors being OK once I saw the clean side of the paper. The Jeep started on the second try.




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  • 2 months later...
On 05/05/2022 at 14:39, V said:

Despite what Jeep have told the DVSA about E10 compatibility for XJ and YJ

Following up from what I posted previously, I found written evidence today to back up my claim that the E10 compatibility information on DVSA is wrong.


In the 1993 Jeep Cherokee Factory Service Manual published by Mopar (Revised 1996), section 'Scheduled Services', '1989-1996 Maintenance', it says:



CAUTION: Exclusive use of gasohol is not recommended. Vehicle test
results have shown that significant fuel system corrosion
can result when gasohol is used exclusively.


CAUTION: Fuel that is more than 5% methanol should not be used in this
vehicle. It can corrode metal parts in the fuel system, and
damage plastic and rubber parts. Even at 5% methanol or less,
solvents and corrosion preventers must be used with this fuel
to avoid these problems.



The definition of Gasohol is E5-E15.

The European Union amended Fuel Quality Directive adopted in 2009 allows up to 3% v/v blend-in of methanol in petrol.

So either way, ethanol and methanol blended fuels are not safe for old Jeeps, but I learned that already the expensive way.

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