NAS-ROW - The Land Rover Defender Forum  

Go Back   NAS-ROW - The Land Rover Defender Forum > NAS-ROW Technical Forums > Defender Technical Discussions

Reply
 
Thread Tools Display Modes
Old 02-25-2018, 10:19 AM   #1
NMEXPAT
Junior Member
 
Join Date: Sep 2017
Location: Houston, TX
Posts: 15
Thanks: 0
Thanked 0 Times in 0 Posts
Default Carb Issues - 1987 3.5 V8

Long time lurker and first time poster. Looking for some direction.

Back in October 2017 I bought an Australian 1987 110 3.5 V8 from Royal Overland in Austin. On the drive home from Austin to Houston, it stopped running. Basically it felt like it was running out of gas, when of course it wasn't empty. It would do this a few more times over the next few weeks, but always start up and drive again after a few hours like nothing happened.

After doing some internet research I decided the fuel pump was slowly dying. I ordered a new fuel pump and other odds and ends from Rovahfarm.

While dropping the fuel tank, I found it was powered by a separate individual +12V source. I didn't trace the wire back, but the vehicle at some point was outfitted with a immobilizer. I think this separate wire could be grounding out randomly or the immobilizer would acting up. This also might be the cause of the random shut downs.

In the end I terminated the single +12V wire and rewired the pump wires to the original wires.

Two weeks ago the stars aligned, I was off work and it wasn't raining. I installed the new fuel pump and fuel filter. I confirmed the fuel pump was wired correctly and running by turning the vehicle without the filter in place. Fuel was coming out. I then installed the fuel filter and tried to start my truck. It initially fired up for a second and then stopped. It wouldn't spark anymore. It cranks but won't fire up.

I pretty sure the carbs are flooded. Due to the vehicle storage location and running out of time I couldn't confirm this 100% but I've flooded cars and bikes before. I'm pretty sure this fuel pump is pumping much better (higher pressure) than the old one that came out of it.

I also didn't check the fuel vapor separator or fuel return line to fuel tank. Fuel should be returning to the fuel tank under normal operation.

Here's my dilemma.
1. I could rebuild the SU carbs and replace the gaskets, needles etc. Hoping the float needle valve will now seal. Probably cost $200
2. Ditch the SU carbs entirely and go to an "american" style carb setup. Looking at $800 cost.

I'm leaning towards #2 since most people post positive results with changing the intake manifold. However, when the truck was running with the original equipment and it ran great. I just want the most reliable and easy to work on setup.

Any other tips before I drop money on carbs? I guess I could install the old pump back in and see if the truck will run, this would only serve to eliminate the suspect wire problem and over pressure but I'd be worried about it dying randomly. I couldn't find any information on the fuel regulator near / on the fuel vapor separator. Hopefully I'm just over looking something simple.

Thanks!
NMEXPAT is offline   Reply With Quote
Old 02-25-2018, 10:42 AM   #2
Red90
Senior Member
 
Join Date: Sep 2017
Location: GWN
Posts: 438
Thanks: 3
Thanked 110 Times in 85 Posts
Default

Adjust the floats, make sure they are not leaking and check the float valves. Sounds like that was the problem from day one. No need for $200, just a little bit of time. It is a simple job.

The Edlebrock (Carter) carbs are not better carbs. If changing to something new, you are better going EFI.
Red90 is offline   Reply With Quote
Old 02-25-2018, 10:43 AM   #3
RDavisinVA
Senior Member
 
RDavisinVA's Avatar
 
Join Date: Nov 2016
Location: VA USA
Posts: 507
Thanks: 30
Thanked 122 Times in 84 Posts
Default

After all the years the 3.5 fuel pumps become suspect.
Why not install a new fuel pump and install a relay powered from the starter lug, but energized by the IG SW.
Then run the output from the relay to the fuel pump.
Wouldn't this ensure fuel delivery?
__________________
RDavisinVA
RDavisinVA is offline   Reply With Quote
Old 02-25-2018, 11:05 AM   #4
NMEXPAT
Junior Member
 
Join Date: Sep 2017
Location: Houston, TX
Posts: 15
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Quote:
Originally Posted by RDavisinVA View Post
After all the years the 3.5 fuel pumps become suspect.
Why not install a new fuel pump and install a relay powered from the starter lug, but energized by the IG SW.
Then run the output from the relay to the fuel pump.
Wouldn't this ensure fuel delivery?
I don't have a fuel deliver problem right now. The new pump is definitely pumping fuel. I think I have a blocked return line problem or a float valve sealing problem.
NMEXPAT is offline   Reply With Quote
Old 02-25-2018, 11:09 AM   #5
NMEXPAT
Junior Member
 
Join Date: Sep 2017
Location: Houston, TX
Posts: 15
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Quote:
Originally Posted by Red90 View Post
Adjust the floats, make sure they are not leaking and check the float valves. Sounds like that was the problem from day one. No need for $200, just a little bit of time. It is a simple job.

The Edlebrock (Carter) carbs are not better carbs. If changing to something new, you are better going EFI.
I'm just unfamiliar with the SU carbs and despite having the workshop manual I remain a little fearfull. I figured if I was going to mess with the carbs I might as well replace the gaskets, seals, floats and valves. I've tried to skimp on rebuilding motorcycle carbs, and it always bites me back.
NMEXPAT is offline   Reply With Quote
Old 02-25-2018, 11:10 AM   #6
NMEXPAT
Junior Member
 
Join Date: Sep 2017
Location: Houston, TX
Posts: 15
Thanks: 0
Thanked 0 Times in 0 Posts
Default

I also forgot to mention at some point in the trucks life it was outfitted with LPG fueling as well. Some of the hardware remains as well, but I'm no certainly no expert.
NMEXPAT is offline   Reply With Quote
Old 02-25-2018, 12:40 PM   #7
RBBailey
Senior Member
 
RBBailey's Avatar
 
Join Date: Nov 2016
Location: Damascus, Oregon
Posts: 1,331
Thanks: 116
Thanked 98 Times in 82 Posts
Member Trucks
Default

I'm not an expert, but I'd say start simple. Just try cleaning the carbs as they sit, then work up from there. I've had several fuel issues go away completely with a simple cleaning.

Also, could it be possible that something is just stuck? Are both carbs being actuated in exactly the same way when the choke and pedal are moved?
__________________
1965 IIa 88"
1988 Saudi 110 300Tdi
1995 RRC LWB
RBBailey is offline   Reply With Quote
Old 02-25-2018, 02:00 PM   #8
Roverman2010
Senior Member
 
Roverman2010's Avatar
 
Join Date: Nov 2016
Location: Galveston Island nr Texas
Posts: 295
Thanks: 10
Thanked 31 Times in 24 Posts
Member Trucks
Default

SU's are not hard to tune, just need to understand them.As long as they are not worn out.
Roverman2010 is offline   Reply With Quote
Old 02-25-2018, 04:54 PM   #9
Red90
Senior Member
 
Join Date: Sep 2017
Location: GWN
Posts: 438
Thanks: 3
Thanked 110 Times in 85 Posts
Default

Quote:
Originally Posted by NMEXPAT View Post
I'm just unfamiliar with the SU carbs and despite having the workshop manual I remain a little fearfull. I figured if I was going to mess with the carbs I might as well replace the gaskets, seals, floats and valves. I've tried to skimp on rebuilding motorcycle carbs, and it always bites me back.
Pull the carbs, turn them over and pull the float bowls. Check valves to make sure they seal (blow into fuel line and then close valve). Check floats to make sure they float and then adjust float height. Super simple. No different than any other carb. All clear in the manual. Nothing to be fearful of.

Don't fix things that are not broken. Your description from the beginning was carb flooding.
Red90 is offline   Reply With Quote
Old 02-26-2018, 10:31 AM   #10
RDavisinVA
Senior Member
 
RDavisinVA's Avatar
 
Join Date: Nov 2016
Location: VA USA
Posts: 507
Thanks: 30
Thanked 122 Times in 84 Posts
Default

We use the Moss 386-390 Grose-Jet on MGs with SU carbs as a trouble free replacement for the older and problematic needle & seat.
This may fit your carbs, Moss could tell you.
__________________
RDavisinVA
RDavisinVA is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

» Log in
User Name Not a member yet?
Register Now!
Password
» Today's Birthdays
None
Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 01:49 AM.


Powered by vBulletin® Version 3.8.10 Release Candidate 2
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.