Random surging while driving

[ISPKI]

Yes! I ended up getting a pack of these from McMaster. They categorized it as 5/16-3/8" but its stamped 8mm-9.5mm and it seems to work perfectly.
It just surprised me that local auto stores dont carry anything this small, Maybe because fuel hose for 1/4" ID is thicker walled and these wouldnt fit?

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[Cant Write]

IF I’m following you correctly, are you sure the hardline from your lift pump to the filter head is your culprit?

Have you tried just running a Jerry can straight to the lift pump and see if you surging issues still happen...

Or are you doing upgrades as you solve your surging?

I ended up using spring hose clamps (constant pressure clamps) like many manufacturers use cause I had them on hand. I figured they’d be fine for low pressure.

 

[Old Goat]

Russ Repair has the Lift Pump to filter head Line Kit.

shop all - Page 3 - Russ Repair

russrepair.com

And the Filter to IP Hard Line delete kit

shop all - Page 4 - Russ Repair

russrepair.com

Reading through this, seems like you are over thinking this fix,
or maybe Iam not reading it right.

I did the LP several years ago, 3/8 Barb fitting at the pump, 3/8" fuel hose up to the Filter and as I remember another barb at the top.

The Filter to IP, I picked up the fittings at the HYD Shop, and used Push Lock Hose.

I use the same Hose Clamps you purchased. You can get them in Stainless Steel as well as plated steel.

Pretty simple repair.


Goat

 

[ISPKI]

IF I’m following you correctly, are you sure the hardline from your lift pump to the filter head is your culprit?

Have you tried just running a Jerry can straight to the lift pump and see if you surging issues still happen...

Or are you doing upgrades as you solve your surging?

I ended up using spring hose clamps (constant pressure clamps) like many manufacturers use cause I had them on hand. I figured they’d be fine for low pressure.

No, im not sure so I figured I would do the low hanging fruit stuff first. Besides, I have no idea as to how long the lines and pump have been on the vehicle.

So, option 2 I suppose .

I did the lift pump, soft line to the lift pump, and replaced the hardline from lift pump to filter head with clear soft line and a check valve.

Seems I may have uncovered some issues. First off, the short section of soft line from the FSV to the lift pump was badly degraded inside (there is ~6" of soft line from the metal line from the FSV to the pump). Inside was broken down into hard chunks.

The hardline from lift to filter was dry, no fuel in it.

Got the hardline from filter to IP off and it's olive seal was gone, only small bits of hard rubber left in there.

Only step I have left is to get the fitting at the IP off and screw the new fitting on with the new hose. Then I should be able to bleed the system and try it out. I would not be surprised if the surging was either from the fuel line break down before the Lift pump or from the fitting at the filter head with the olive disintigrated. Makes me worried about where the bits for that olive went...

 

[Cant Write]

Whoa!! Sounds like you have uncovered lots of little things that could have added up to your issues.

I hope when you fire it up, the problem is solved!! Nice job!!

Use the Jerry can as a last resort ... hair pulling ... head scratching ... ale swirlin’ .... fix all Diagnosis!!

 

[ISPKI]

The ale swirlin' is particularly helpful during the diagnostic procedure. Slàinte!

 

[chillman88]

I received all my fittings and hose but when I went to setup the new lift pump, i found that the 1/4 NPT elbow I got for it doesnt fit. I believe the thread is 5/8-18, however, I need to figure out how to get it to seal. The bottom of the lift pump fitting is what appears to be a 45 degree flare for hardline and I am not 100% sure they make an adapter to convert from that flare to an NPT.

Heres what I am thinking of doing. I can get male flare fitting for 3/8" hardline that has the 5/8-18 thread and 1/4NPT female on the other end. I can then turn the flared male end down into a female flare, matching the flare of the lift pump. The fitting is brass so it *might* seal metal to metal.

So I could take this fitting:

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And machine it into this fitting:

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And hopefully due to the pump being steel and the fitting being Brass, achieve a metal on metal airtight seal.

Alternatively, I could cut the end of the fitting flat and place a Viton O ring inside the pump side and compress it using this fitting.

They do sell a 3/8 inverted flare adapter like that. I bought mine at Advance Auto. My hardline started leaking so I just bought that and an NPT to hose barb adapter and ran hose over the tube and forgot about it until you posted this

 

[KenIDI93]

My '93 idi is having speedometer stuttering/bouncing issues and fuel lines and possibly the IP are on the list of things to check.

You folks in this Post have been very helpful - appreciate everyone's input.
For us amateurs out here, Posts like this are of tremendous value and insight.