Losing Prime

The place to discuss problems and routine maintenance questions and tips. This is for topics that are specifically diesel-related.
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Dongshoreman
Regular Member
Posts: 77
Joined: Thu Jun 11, 2015 11:34 am
Location: Southern California
Isuzu vehicle(s): 1983 diesel short bed

Re: Losing Prime

Postby Dongshoreman » Sun Jun 10, 2018 9:15 pm

Sadly I think my last post was a bit premature. After replacing the bleed screw o-ring and a successful test after 24 hrs, I got into my P'up a couple days later and I had lost prime again. I decided to change the fuel filter since it was due anyway, and what I found was kind of interesting. Threaded onto the bottom of the plastic sensor assembly that screws on to the filter is a brass hose barb that holds the fuel hose going to the hand pump. I decided to take it off and when I put my wrench on it I found it surprisingly loose. I probably could have taken it off by hand. Upon inspection I found that the barb was missing an o-ring. See the photo below, I put an arrow where I think the second o-ring should go. Please anyone feel free to weigh in on this if I am mistaken.
hose barb with arrow.jpg

Another reason why I am pretty sure that this hose barb needs two o-rings is because the lip of the edge of the threads is fluted and looks like it is designed to accept an o-ring. Picture below:
sensor assembly.jpg


I ended up replacing both o-rings on the hose barb and it seemed to make a nice seal once I installed it. Here's a photo of the hose barb with both o-rings and their sizes:

hose barb two orings.jpg

After installing two new o-rings on the hose barb I realized that the plastic bleeder screw is similar. I inspected the bleed screw and found basically the same setup: A gap on the top of the bleeder screw that fits an o-ring, and the same fluted lip on the threads on the hand pump. I installed a second o-ring on the bleeder screw as well. Here is a picture of the bleed screw with both o-rings and their sizes:
Plastic bleed screw.jpg


I ran out of time today to finish the job, but I will try to prime the system and start up tomorrow, and then test again after letting it sit for a day or so. I will try to post another update later on this week with a verdict on whether or not this fixed the problem.

Thanks,
Jake
1983 Diesel Shortbed

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puttputtinpup
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Posts: 10242
Joined: Sat Oct 08, 2005 5:18 am
Location: Winston Salem, NC

Re: Losing Prime

Postby puttputtinpup » Mon Jun 11, 2018 4:53 am

This is very good information! Thanks Jake. Ill save tjis in my. Personal archives for quick reference in the future.

SactoTodd
Regular Member
Posts: 14
Joined: Wed Jul 16, 2008 5:41 pm
Location: Sacramento, Ca

Re: Losing Prime

Postby SactoTodd » Sun Jul 01, 2018 8:55 pm

2sk8 wrote:I have 2 new units for sale if you wanna buy one.


Do you by chance still have 1? Cost shipped to 95742

-Todd
1982 Diesel P'up - 5-sp, Longbed, Sweet blue herringbone interior

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puttputtinpup
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Posts: 10242
Joined: Sat Oct 08, 2005 5:18 am
Location: Winston Salem, NC

Re: Losing Prime

Postby puttputtinpup » Sun Jul 01, 2018 9:14 pm

SactoTodd wrote:
2sk8 wrote:I have 2 new units for sale if you wanna buy one.


Do you by chance still have 1? Cost shipped to 95742

-Todd

to make sure 2sk8 gets your question, you could send him a PM (private msg).

2sk8
Regular Member
Posts: 197
Joined: Thu Apr 17, 2008 2:59 am
Location: California
Isuzu vehicle(s): 91 Isuzu Pick up converted to diesel

Re: Losing Prime

Postby 2sk8 » Mon Jul 02, 2018 3:06 pm

Hi Todd,

the primer pump is $39.99 with free shipping by US mail.

I have 2 units.

I just sent you a private message so you can send me a paypal.

masonandford
Regular Member
Posts: 25
Joined: Sun Mar 11, 2012 3:43 pm
Location: Buckingham VA
Isuzu vehicle(s): 81 chevy luv 2wd diesel from slygopup, 84 diesel 2wd long bed , 83 4x4 diesel with grease conversion, 84 diesel 2wd flat bed parts truck

Re: Losing Prime

Postby masonandford » Wed Aug 01, 2018 8:21 pm

im having the exact same issue! my starter just quit on me because of it today. :( glad to have all these tips.
- Mason - 81 diesel Chevy Luv 2wd
84 diesel p'up long bed 5spd 2wd RIP

FiatSpider2
Regular Member
Posts: 166
Joined: Sat Dec 06, 2014 7:30 am
Location: Sunny Tampa Bay Florida

Re: Losing Prime

Postby FiatSpider2 » Sat Aug 04, 2018 11:33 pm

Since I installed an electric lift pump I have missed out on all these issues.

This one is distributed under a number of name brands:
Image
FiatSpider2 (4FB1 Isuzu Diesel powered 1978 Fiat Spider)


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