Quadrise said it now expects the trial in Morocco of its alternative and less polluting shipping fuel MSAR to be completed in early September after design issues with the fuel pump.
A replacement pump of alternative design is being shipped to Morocco for installation later this month.
Quadrise had already been forced to put completion of the trial back once due to a mechanical failure in May.
Jason Miles, Quadrise's chief executive, said: "The design issues experienced with the pumps to date were not foreseeable and are very frustrating for all concerned.
“We remain highly confident that once the trial resumes following the installation of an alternative pump, we will be able to demonstrate the benefits of MSAR and bioMSAR in the commercial trial for our supportive client."