• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

poor starting on low tank (its not the pump)

autoloclys

Member
Joined
Dec 20, 2016
Location
Boston MA
yes ive already changed the in-tank pump

my '92 240 wagon (+T LH 2.4 with a TLAO chip)

is frequently hard to start when the tank is low. but runs fine otherwise. I swapped the in tank pump for new last week and still have the issue. Often i can get it going with some gas pedal input.

I am assuming the main pump is unlikely to fail "a little bit", and its only 3 years old anyway. The whole fuel system (filter, both pumps, supply and return fuel lines, FPR and injectors, are all less than 5 years old.

what are my next steps for diagnosing?

left to my own devices inclined to look at the IAC valve or fuel pressure, but am i missing something?
 

2manyturbos

Moderator
Joined
Mar 8, 2003
Location
Monroe, OR USA
Possibly. Did you check whether the pump is wired correctly? If not, just pull one of the leads running to the main pump, remove the fuel line from the rail and cycle the key a few times or crank the starter over and see if you are getting fuel flowing out of the line. Many of the new replacement pumps are wired backwards.
 

cleanflametrap

Active member
Joined
Sep 3, 2009
Location
near baltimore
Checking tank pump

I didn't spill any fuel doing this:

tank0904.jpg


tank1059.jpg


tank1023.jpg


And if you pull the electrical plug for the tank pump/sender, you could connect an external battery to test it with reversed polarity. The tank pump is centrifugal, so it won't "suck", just be a little weaker if the polarity is reversed due to the angle in the pump's volute.

tank03.jpg


Not sure how much volume a stalled main roller cell pump will let by depending on its age. One 3 years old might be pretty tight yet.
 
Joined
Dec 1, 2021
Other possibility is that when you swapped the in tank pump the new rubber hose between the pump and spout out isn't properly seated so leaks (i.e. losing some of the flow) rather than fully fully off where in tank sender really doesn't help you at all (and then starting would be impossible rather than just difficult.

but polarity sounds more likely.
 

Radtap

Active member
Joined
Dec 16, 2020
Location
Sweat zone, Arizona
Did you use proper submersible fuel line to connect the pump to the sending unit or just generic stuff. Did you replace the sending unit recently? There was an issue with some being wired backwards though I haven?t run into that after ordering a few URO units
 

dl242gt

The world of the smiling Dogo
Joined
Jun 21, 2002
Location
S NJ, a suburb of Phila.
Are you sure the pump is running? Because I've experienced the ground tab on the sender failing. Then the pump doesn't run. To fix that you have to drill a small hole in the sender and crimp a ring terminal to the ground wire. Then use a serrated washer under the ring terminal for a good connection.
 

dl242gt

The world of the smiling Dogo
Joined
Jun 21, 2002
Location
S NJ, a suburb of Phila.
You can remove fuse 4 or 5 depending on the year. Then connect your amp meter across the fuse tabs. That current reading will tell you if the pump is running. Usually, about 1.7-2 amps for the stock n/a lift pump. The turbo one is about an amp more.
 

Kjets On a Plane

Active member
Joined
Nov 12, 2002
Location
Californicated Oregone
I didn't spill any fuel doing this:
http://cleanflametrap.com/tank0904.jpg
http://cleanflametrap.com/tank1059.jpg
http://cleanflametrap.com/tank1023.jpg

And if you pull the electrical plug for the tank pump/sender, you could connect an external battery to test it with reversed polarity. The tank pump is centrifugal, so it won't "suck", just be a little weaker if the polarity is reversed due to the angle in the pump's volute.

http://cleanflametrap.com/tank03.jpg

Not sure how much volume a stalled main roller cell pump will let by depending on its age. One 3 years old might be pretty tight yet.
On the CI cars, I?d block the return to test the main pump? if the pump briefly stalled or immediately wrapped the gauge to the ~150psi internal relief (whatever that is in metric units?) I?d pronounce it ?serviceable?, especially if it sounded smooth/ current draw looked good on the scope with the brushes turning each winding on & off?

Idk what the hell im doing?
If it cavitated, sounded gurgly or was at all slow to build pressure, I?d pronounce it ?marginal at best? as main pumps go?

?78-?85 supposedly has a 3psi lift pump, ?86+ has a 6psi tank pump.
On the 240Ts, I?d cut the tube on the sender and use the tall 700T style tall lift pump I confess?
Never heard the main pump run so quiet in years on those cars after that?

That said, I have mixed feelings about the modification and stirring or frothing the fuel around more on the later 240 tank setup with the 7/9?turbo in tank pump ?upgrade??
I don?t run the tank below the ?red,? (Never drier than 12.8-13.1 gallons and make a habit of filling the tank completely & keep ~25-100 gallons of gas around or used to @ $1 off/gallon35 gallon max allowable fill ups) don?t park in the sun on hot days over hot pavement to top off with/don?t run around on a nearly dry tank for prolonged periods with a little bit of hot gas/sediment on the bottom the tank?

The pump seems least stressed on the 2.5bar fpr LH efi 240s?I kinda think they had that aspect (pump & filter longevity / service life with plenty of neglect?) right for passing evap emissions and everything else in the 1960s chassis with evap compliant tank band-aided into what started out as a ?67 140 (I think they had D-jet in mind as an option the way the 140 FI tank is designed and those cars came with alternators basically from inception in the USA market, however?) running lower pressure with a bit stronger lift pump ?86-?88?

I half suspect they went to one parts bin that shared more with the 700s as well as being CA emissions compliant with EGR & same LH2.4 parts bin as the 7/9s on the ?89+ 240s??

Kinda redneck/shade tree in my case & not particularly scientific?
Maybe I?m way off base in my limited understanding of how this thing is supposed to work?

The last of the 240 senders have better sealed terminals & more fuel rot resistant vibration damping accordion hose from the tank pump if not remember well?

Clamp on return line on ?86+ fuel level senders?
Push-on PITA PET with the bubble flare on the return to be careful with on the -?85 senders should you choose to keep the original -?85 type sender if possible?

Nothing lasts forever, obviously, but if the pickup sock isn?t all gross/clogged or dissolved/shredded & the owner doesn?t run the tank low for prolonged periods or park over hot pavement & changes the filter on time, pump longevity seems quite good?

Hot weather cars running around below half a tank of fuel with clogged or gross sock & filters parked in the sun I changed considerably more pumps and filters on if I remember well (such a one has any memory left / try to be careful around all those gas fumes?)?
?I?m reasonably certain with the OE quality parts, the pumps can last 20-30 years & 200kmi +, particularly on the 2.5 Bar FPR EFI 240s?YMMV?

Idk that the dealer or formerly reputable brands are reliable sources of OEM or better quality hoses & pumps, anymore? Even if properly installed & verified good?
 
Last edited:

autoloclys

Member
Joined
Dec 20, 2016
Location
Boston MA
thanks for all the advice, i picked up a fuel pressure test kit and am struggling to figure out how to connect it to the rail. My car (a '92 wagon, LH2.4) does not have the Schrader valve on the fuel rail. I attempted to connect inline with the FPR, but couldn't read any pressure even with the car running. my next idea is to figure out the connector spec for the fuel supply line and make up something to put inline in front of the fuel rail

Does the diameter change of the fuel rail pipe in front of the FPR limit pressure? maybe I was wrong to think the FPR sees constant pressure at idle? does my cheap test kit without a relief button mean its airbound and i need to spend more money?

ive also now seen it no start/hard start on a full tank, so now im a little nervous about driving anywhere far from home.
 

rb92673

racecar
Joined
Jan 17, 2017
Location
San Clemente
I believe it is M14 x 1.5 for the connection of the fuel line to fuel rail. That is where I connected a fuel pressure test kit.
 

dl242gt

The world of the smiling Dogo
Joined
Jun 21, 2002
Location
S NJ, a suburb of Phila.
You need a an adapter fitting to go between the feed line and the rail. There was an old thread about the fitting you can buy from Pro Tool. Something like 'LH2.4 adapter fitting' should find the old thread.
 

dl242gt

The world of the smiling Dogo
Joined
Jun 21, 2002
Location
S NJ, a suburb of Phila.
You need a an adapter fitting to go between the feed line and the rail. There was an old thread about the fitting you can buy from Pro Tool. Something like 'LH2.4 adapter fitting' should find the old thread.

I think the name of the place was Tool Source. Here it is. I admit I haven't used
it yet as my car has the shrader valve in the fuel rail. Terrible photo but it's
cheap enough to try. https://www.toolsource.com/volvo-to...njection-adapter-14mm-lhjetronic-p-55212.html
 

autoloclys

Member
Joined
Dec 20, 2016
Location
Boston MA
Thanks for the adapter info. I?ve confirmed that fuel pressure is good both normally and when the hard starting hits me. So that seems to rule out fuel delivery to the rail

What are the next things to look at?

Possibly useful info
-it?s never happened with a warm engine, only if the car is sitting overnight or longer
-after it happens, if I wait a couple days. It?s starts normally without changing anything
-it ?might? be tied to humidity. Damp mornings seem to be when it happens

Is there a system meant to run onto for cold starts that might be the issue?
 

dl242gt

The world of the smiling Dogo
Joined
Jun 21, 2002
Location
S NJ, a suburb of Phila.
Have you checked the distributor cap for cracks? They can be very small and hard to find. It also may be good to check the resistance of the plug wires.
 

283SD

Active member
Joined
Mar 8, 2008
My '90 had a hard start issue, replaced the main pump, took it apart, of the two magnets in the pump one was broken causing it to start hard. IDN if this helps.
 

Harry Tuttle

Active member
Joined
Jun 2, 2006
Location
in your ducts
-it ?might? be tied to humidity. Damp mornings seem to be when it happens
dl242gt said:
Have you checked the distributor cap for cracks? They can be very small and hard to find. It also may be good to check the resistance of the plug wires.

Good advice from Dave. Though I have never done it, I have heard that if you spray a mist of water on the plug wires in the dark, and they are shot, you will see arcing all over the place.
 

dl242gt

The world of the smiling Dogo
Joined
Jun 21, 2002
Location
S NJ, a suburb of Phila.
Good advice from Dave. Though I have never done it, I have heard that if you spray a mist of water on the plug wires in the dark, and they are shot, you will see arcing all over the place.

Yes, I have used this several times. It looks amazing if you like electricity. I even
found a plug wire that was arcing through the boot to the head using this method.
 
Top